diff --git a/.changeset/funny-dingos-spend.md b/.changeset/funny-dingos-spend.md
new file mode 100644
index 0000000000..077b9e09e4
--- /dev/null
+++ b/.changeset/funny-dingos-spend.md
@@ -0,0 +1,7 @@
+---
+"@redocly/cli": minor
+"@redocly/openapi-core": minor
+"@redocly/respect-core": minor
+---
+
+Added support for OpenAPI `allowReserved` on query parameters in Respect.
diff --git a/packages/core/src/types/arazzo.ts b/packages/core/src/types/arazzo.ts
index db00fad02e..350a7dd098 100755
--- a/packages/core/src/types/arazzo.ts
+++ b/packages/core/src/types/arazzo.ts
@@ -145,6 +145,11 @@ const Parameter: NodeType = {
       description: 'REQUIRED. The name of the parameter. Parameter names are case sensitive.',
     },
     value: {}, // any
+    allowReserved: {
+      type: 'boolean',
+      description:
+        'When true, RFC 3986 reserved characters in query parameter values are left unencoded.',
+    },
   },
   required: ['name', 'value'],
   extensionsPrefix: 'x-',
diff --git a/packages/respect-core/src/arazzo-schema.ts b/packages/respect-core/src/arazzo-schema.ts
index 2694ae6622..e1d263fcba 100644
--- a/packages/respect-core/src/arazzo-schema.ts
+++ b/packages/respect-core/src/arazzo-schema.ts
@@ -161,6 +161,7 @@ export const parameter = {
         value: {
           oneOf: [{ type: 'string' }, { type: 'number' }, { type: 'boolean' }],
         },
+        allowReserved: { type: 'boolean' },
       },
       required: ['name', 'value'],
       additionalProperties: false,
diff --git a/packages/respect-core/src/modules/__tests__/description-parser/get-request-data-from-openapi.test.ts b/packages/respect-core/src/modules/__tests__/description-parser/get-request-data-from-openapi.test.ts
new file mode 100644
index 0000000000..260bdc67b0
--- /dev/null
+++ b/packages/respect-core/src/modules/__tests__/description-parser/get-request-data-from-openapi.test.ts
@@ -0,0 +1,41 @@
+import { logger } from '@redocly/openapi-core';
+
+import type { OperationDetails } from '../../description-parser/get-operation-from-description.js';
+import { getRequestDataFromOpenApi } from '../../description-parser/get-request-data-from-openapi.js';
+
+describe('getRequestDataFromOpenApi', () => {
+  it('should pass allowReserved only on query parameters where it is set', () => {
+    const operation = {
+      method: 'get',
+      path: '/search',
+      descriptionName: 'test',
+      pathParameters: [],
+      parameters: [
+        {
+          name: 'filter',
+          in: 'query',
+          required: true,
+          allowReserved: true,
+          schema: { type: 'string' },
+        },
+        {
+          name: 'page',
+          in: 'query',
+          required: true,
+          example: 1,
+          schema: { type: 'integer' },
+        },
+      ],
+      responses: {},
+    } as OperationDetails;
+
+    const result = getRequestDataFromOpenApi(operation, logger);
+
+    const filterParam = result.parameters.find((p) => p.name === 'filter');
+    expect(filterParam?.allowReserved).toBe(true);
+
+    const pageParam = result.parameters.find((p) => p.name === 'page');
+    expect(pageParam).toBeDefined();
+    expect(pageParam?.allowReserved).toBeUndefined();
+  });
+});
diff --git a/packages/respect-core/src/modules/__tests__/flow-runner/prepare-request.test.ts b/packages/respect-core/src/modules/__tests__/flow-runner/prepare-request.test.ts
index 8748bb6a78..6c36911dbf 100644
--- a/packages/respect-core/src/modules/__tests__/flow-runner/prepare-request.test.ts
+++ b/packages/respect-core/src/modules/__tests__/flow-runner/prepare-request.test.ts
@@ -427,6 +427,63 @@ describe('prepareRequest', () => {
     expect(requestBody).toEqual(undefined);
   });
 
+  it('should pass allowReserved on query params when OpenAPI operation has allowReserved', async () => {
+    const allowReservedCtx = {
+      ...ctx,
+      $sourceDescriptions: {
+        cats: {
+          paths: {
+            '/search': {
+              get: {
+                operationId: 'searchAllowReserved',
+                summary: 'Search',
+                parameters: [
+                  {
+                    name: 'filter',
+                    in: 'query',
+                    required: true,
+                    allowReserved: true,
+                    schema: { type: 'string' },
+                  },
+                ],
+                responses: { '200': { description: 'ok' } },
+              },
+            },
+          },
+          servers: [{ url: 'https://api.example.com/' }],
+        },
+      },
+      workflows: [
+        {
+          workflowId: 'search-workflow',
+          steps: [
+            {
+              stepId: 'search-step',
+              operationId: 'cats.searchAllowReserved',
+              checks: [],
+              response: {},
+            },
+          ],
+        },
+      ],
+      $workflows: {
+        'search-workflow': {
+          steps: {
+            'search-step': { request: {} },
+          },
+        },
+      },
+      $steps: {
+        'search-step': { request: {} },
+      },
+    } as unknown as TestContext;
+    const searchStep = allowReservedCtx.workflows[0].steps[0];
+    const { parameters } = await prepareRequest(allowReservedCtx, searchStep, 'search-workflow');
+    const filterParam = parameters.find((p) => p.name === 'filter');
+    expect(filterParam).toBeDefined();
+    expect(filterParam?.allowReserved).toBe(true);
+  });
+
   it('should set apiClient step params when descriptionOperation not provided', async () => {
     const step = {
       stepId: 'get-breeds-step',
diff --git a/packages/respect-core/src/modules/description-parser/get-request-data-from-openapi.ts b/packages/respect-core/src/modules/description-parser/get-request-data-from-openapi.ts
index 457da50837..d48f971150 100644
--- a/packages/respect-core/src/modules/description-parser/get-request-data-from-openapi.ts
+++ b/packages/respect-core/src/modules/description-parser/get-request-data-from-openapi.ts
@@ -72,6 +72,7 @@ function transformParameters(params: Parameter[], logger: LoggerInterface): Para
           name: parameter.name,
           in: parameter.in,
           value: generateExampleValue(parameter, logger),
+          ...(parameter.allowReserved && { allowReserved: parameter.allowReserved }),
         } as ParameterWithIn;
       }
       // Return undefined for non-matching parameters
diff --git a/packages/respect-core/src/types.ts b/packages/respect-core/src/types.ts
index 448498a3cf..cfc81e18b7 100644
--- a/packages/respect-core/src/types.ts
+++ b/packages/respect-core/src/types.ts
@@ -59,6 +59,7 @@ export type AdditionalParameterProperties = {
   schema?: Record<string, any>;
   example?: unknown;
   examples?: Record<string, any> | unknown;
+  allowReserved?: boolean;
 };
 type ExtendedParameter<T> = T & AdditionalParameterProperties;
 export type Parameter = ExtendedParameter<ArazzoParameter>;
diff --git a/packages/respect-core/src/utils/__tests__/url-encoding.test.ts b/packages/respect-core/src/utils/__tests__/url-encoding.test.ts
new file mode 100644
index 0000000000..c893a4b334
--- /dev/null
+++ b/packages/respect-core/src/utils/__tests__/url-encoding.test.ts
@@ -0,0 +1,33 @@
+import { encodeURIValue, buildQueryString } from '../url-encoding.js';
+
+describe('encodeURIValue', () => {
+  it('should encode reserved chars when allowReserved is false (default)', () => {
+    expect(encodeURIValue("a!b'c(d)e*f/g")).toBe('a%21b%27c%28d%29e%2Af%2Fg');
+  });
+
+  it('should leave RFC 3986 reserved chars unencoded when allowReserved is true', () => {
+    const reserved = ":/?#[]@!$&'()*+,;=";
+    expect(encodeURIValue(reserved, true)).toBe(reserved);
+  });
+
+  it("should leave chars that encodeURIComponent does not encode (!'()*) unencoded when allowReserved true", () => {
+    const encoded = "a!b'c(d)e*f";
+    expect(encodeURIValue(encoded, true)).toBe(encoded);
+  });
+
+  it('should encode non-reserved chars even when allowReserved is true', () => {
+    expect(encodeURIValue('a b', true)).toBe('a%20b');
+  });
+});
+
+describe('buildQueryString', () => {
+  it('should encode reserved chars depending on allowReserved', () => {
+    const raw = 'https://example.com/path/to;x,y(z)a*b.c[1]@v';
+    const query = buildQueryString([
+      { name: 'raw', value: raw, allowReserved: true },
+      { name: 'encoded', value: raw },
+    ]);
+    expect(query).toContain(`raw=${raw}`);
+    expect(query).toContain(`encoded=${encodeURIValue(raw, false)}`);
+  });
+});
diff --git a/packages/respect-core/src/utils/api-fetcher.ts b/packages/respect-core/src/utils/api-fetcher.ts
index 4376b9102f..df6201e583 100644
--- a/packages/respect-core/src/utils/api-fetcher.ts
+++ b/packages/respect-core/src/utils/api-fetcher.ts
@@ -23,6 +23,7 @@ import { isBinaryContentType } from './binary-content-type-checker.js';
 import { generateDigestAuthHeader } from './digest-auth/generate-digest-auth-header.js';
 import { parseWwwAuthenticateHeader } from './digest-auth/parse-www-authenticate-header.js';
 import { isEmpty } from './is-empty.js';
+import { buildQueryString } from './url-encoding.js';
 
 interface IFetcher {
   verboseLogs?: VerboseLog;
@@ -142,7 +143,7 @@ export class ApiFetcher implements IFetcher {
     }
 
     const headers: Record<string, string> = {};
-    const searchParams = new URLSearchParams();
+    const searchParams = [];
     const pathParams: Record<string, string | number | boolean> = {};
     const cookies: Record<string, string> = {};
 
@@ -152,7 +153,11 @@ export class ApiFetcher implements IFetcher {
           headers[param.name.toLowerCase()] = String(param.value);
           break;
         case 'query':
-          searchParams.set(param.name, String(param.value));
+          searchParams.push({
+            name: param.name,
+            value: String(param.value),
+            allowReserved: param.allowReserved,
+          });
           break;
         case 'path':
           pathParams[param.name] = String(param.value);
@@ -163,6 +168,8 @@ export class ApiFetcher implements IFetcher {
       }
     }
 
+    const queryString = buildQueryString(searchParams);
+
     if ((isPlainObject(requestBody) || Array.isArray(requestBody)) && !headers['content-type']) {
       headers['content-type'] = 'application/json';
     }
@@ -174,9 +181,7 @@ export class ApiFetcher implements IFetcher {
     }
 
     const resolvedPath = resolvePath(path, pathParams) || '';
-    const pathWithSearchParams = `${resolvedPath}${
-      searchParams.toString() ? '?' + searchParams.toString() : ''
-    }`;
+    const pathWithSearchParams = `${resolvedPath}${queryString ? `?${queryString}` : ''}`;
     const resolvedServerUrl = resolvePath(serverUrl.url, pathParams) || '';
     const urlToFetch = `${trimTrailingSlash(resolvedServerUrl)}${pathWithSearchParams}`;
 
diff --git a/packages/respect-core/src/utils/url-encoding.ts b/packages/respect-core/src/utils/url-encoding.ts
new file mode 100644
index 0000000000..1ffeb3514c
--- /dev/null
+++ b/packages/respect-core/src/utils/url-encoding.ts
@@ -0,0 +1,41 @@
+const RESERVED_CHARS = ":/?#[]@!$&'()*+,;=";
+const EXPLICITLY_ENCODED_CHARS = new Set(['!', "'", '(', ')', '*']);
+
+function toPercentEncoded(char: string): string {
+  if (EXPLICITLY_ENCODED_CHARS.has(char)) {
+    return `%${char.charCodeAt(0).toString(16).toUpperCase()}`;
+  }
+  return encodeURIComponent(char);
+}
+
+/**
+ * Encodes value for query string.
+ * @param allowReserved – when true, reserved chars (:/?#[]@!$&'()*+,;=) stay unencoded (RFC 3986).
+ */
+export function encodeURIValue(value: string, allowReserved = false): string {
+  let encodedValue = encodeURIComponent(value).replace(
+    /[!'()*]/g,
+    (c) => `%${c.charCodeAt(0).toString(16).toUpperCase()}`
+  );
+  if (!allowReserved) return encodedValue;
+
+  const RESERVED_PERCENT_MAP = [...RESERVED_CHARS].map((char) => ({
+    char,
+    encoded: toPercentEncoded(char),
+  }));
+
+  for (const { char, encoded } of RESERVED_PERCENT_MAP) {
+    encodedValue = encodedValue.split(encoded).join(char);
+  }
+  return encodedValue;
+}
+
+export function buildQueryString(
+  params: Array<{ name: string; value: string; allowReserved?: boolean }>
+): string {
+  return params
+    .map(
+      (p) => `${encodeURIComponent(p.name)}=${encodeURIValue(p.value, p.allowReserved === true)}`
+    )
+    .join('&');
+}
diff --git a/tests/e2e/respect/allow-reserved-query-param/__snapshots__/allow-reserved-query-param.test.ts.snap b/tests/e2e/respect/allow-reserved-query-param/__snapshots__/allow-reserved-query-param.test.ts.snap
new file mode 100644
index 0000000000..09e979f24c
--- /dev/null
+++ b/tests/e2e/respect/allow-reserved-query-param/__snapshots__/allow-reserved-query-param.test.ts.snap
@@ -0,0 +1,55 @@
+// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+exports[`should leave reserved chars unencoded in query when allowReserved is true 1`] = `
+"──────────────────────────────────────────────────────────────────────────────── 
+ 
+  Running workflow allow-reserved-query-param.arazzo.yaml / allow-reserved 
+ 
+  ✓ GET https://httpbin.org/get - step get-with-allow-reserved 
+
+    Request URL: https://httpbin.org/get/?filter=https://example.com/path/to;x,y(z)a*b.c[1]@v 
+ 
+
+    Response status code: 200
+    Response time: <test> ms
+    Response Headers: <response headers test>
+    Response Size: <test> bytes
+    Response Body:
+      {
+        "args": {
+          "filter": "https://example.com/path/to;x,y(z)a*b.c[1]@v"
+        },
+        "headers": {
+          "Accept": "*/*",
+          "Accept-Encoding": "br, gzip, deflate",
+          "Accept-Language": "*",
+          "Host": "httpbin.org",
+          "Sec-Fetch-Mode": "cors",
+          "User-Agent": "undici",
+          "X-Amzn-Trace-Id": "<trace-id>"
+        },
+        "origin": "<origin>",
+        "url": "https://httpbin.org/get?filter=https:%2F%2Fexample.com%2Fpath%2Fto%3Bx,y(z)a*b.c[1]%40v"
+      } 
+ 
+    ✓ success criteria check - $statusCode == 200
+    ✓ success criteria check - $response.body#/args/filter == "https://example.co...
+ 
+ 
+  Summary for allow-reserved-query-param.arazzo.yaml
+  
+  Workflows: 1 passed, 1 total
+  Steps: 1 passed, 1 total
+  Checks: 2 passed, 2 total
+  Time: <test>ms 
+ 
+ 
+┌────────────────────────────────────────────────────────────────────────────────┬────────────┬─────────┬─────────┬──────────┐
+│ Filename                                                                       │ Workflows  │ Passed  │ Failed  │ Warnings │
+├────────────────────────────────────────────────────────────────────────────────┼────────────┼─────────┼─────────┼──────────┤
+│ ✓ allow-reserved-query-param.arazzo.yaml                                       │ 1          │ 1       │ -       │ -        │
+└────────────────────────────────────────────────────────────────────────────────┴────────────┴─────────┴─────────┴──────────┘
+ 
+
+"
+`;
diff --git a/tests/e2e/respect/allow-reserved-query-param/allow-reserved-query-param.arazzo.yaml b/tests/e2e/respect/allow-reserved-query-param/allow-reserved-query-param.arazzo.yaml
new file mode 100644
index 0000000000..aaffb8b292
--- /dev/null
+++ b/tests/e2e/respect/allow-reserved-query-param/allow-reserved-query-param.arazzo.yaml
@@ -0,0 +1,23 @@
+arazzo: 1.0.1
+info:
+  title: Allow reserved query params (OpenAPI allowReserved)
+  version: 1.0.0
+sourceDescriptions:
+  - name: museum-api
+    type: openapi
+    url: ../museum-api.yaml
+workflows:
+  - workflowId: allow-reserved
+    steps:
+      - stepId: get-with-allow-reserved
+        x-operation:
+          url: https://httpbin.org/get
+          method: get
+        parameters:
+          - in: query
+            name: filter
+            value: "https://example.com/path/to;x,y(z)a*b.c[1]@v"
+            allowReserved: true
+        successCriteria:
+          - condition: $statusCode == 200
+          - condition: $response.body#/args/filter == "https://example.com/path/to;x,y(z)a*b.c[1]@v"
diff --git a/tests/e2e/respect/allow-reserved-query-param/allow-reserved-query-param.test.ts b/tests/e2e/respect/allow-reserved-query-param/allow-reserved-query-param.test.ts
new file mode 100644
index 0000000000..5020016533
--- /dev/null
+++ b/tests/e2e/respect/allow-reserved-query-param/allow-reserved-query-param.test.ts
@@ -0,0 +1,21 @@
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+import { getCommandOutput, getParams } from '../../helpers.js';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+
+function normalizeHttpbinOutput(output: string): string {
+  return output
+    .replace(/"X-Amzn-Trace-Id": "Root=[^"]+"/g, '"X-Amzn-Trace-Id": "<trace-id>"')
+    .replace(/"origin": "\d+\.\d+\.\d+\.\d+"/g, '"origin": "<origin>"');
+}
+
+test('should leave reserved chars unencoded in query when allowReserved is true', () => {
+  const indexEntryPoint = join(process.cwd(), 'packages/cli/lib/index.js');
+  const fixturesPath = join(__dirname, 'allow-reserved-query-param.arazzo.yaml');
+  const args = getParams(indexEntryPoint, ['respect', fixturesPath, '--verbose']);
+
+  const result = getCommandOutput(args);
+  expect(normalizeHttpbinOutput(result)).toMatchSnapshot();
+}, 60_000);