diff --git a/.changeset/chilled-wolves-pump.md b/.changeset/chilled-wolves-pump.md
new file mode 100644
index 0000000000..1802a812c1
--- /dev/null
+++ b/.changeset/chilled-wolves-pump.md
@@ -0,0 +1,5 @@
+---
+"@hey-api/openapi-ts": patch
+---
+
+parser: merge `default` keyword with `$ref` in OpenAPI 3.1
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/valibot/default/valibot.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/valibot/default/valibot.gen.ts
index badfc0b767..3bc01e4f18 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/valibot/default/valibot.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/valibot/default/valibot.gen.ts
@@ -1455,7 +1455,9 @@ export const vCallWithDefaultParametersData = v.object({
             'Error'
         ])),
         parameterModel: v.optional(v.union([
-            vModelWithString,
+            v.optional(vModelWithString, {
+                prop: 'Hello World!'
+            }),
             v.null()
         ]))
     }))
@@ -1473,7 +1475,9 @@ export const vCallWithDefaultOptionalParametersData = v.object({
             'Warning',
             'Error'
         ])),
-        parameterModel: v.optional(vModelWithString)
+        parameterModel: v.optional(vModelWithString, {
+            prop: 'Hello World!'
+        })
     }))
 });
 
diff --git a/packages/openapi-ts-tests/zod/v3/__snapshots__/3.1.x/mini/default/zod.gen.ts b/packages/openapi-ts-tests/zod/v3/__snapshots__/3.1.x/mini/default/zod.gen.ts
index 96b8cd3542..2a97dcfe22 100644
--- a/packages/openapi-ts-tests/zod/v3/__snapshots__/3.1.x/mini/default/zod.gen.ts
+++ b/packages/openapi-ts-tests/zod/v3/__snapshots__/3.1.x/mini/default/zod.gen.ts
@@ -1486,7 +1486,9 @@ export const zCallWithDefaultParametersData = z.object({
             'Error'
         ])),
         parameterModel: z.optional(z.union([
-            zModelWithString,
+            z._default(zModelWithString, {
+                prop: 'Hello World!'
+            }),
             z.null()
         ]))
     }))
@@ -1504,7 +1506,9 @@ export const zCallWithDefaultOptionalParametersData = z.object({
             'Warning',
             'Error'
         ])),
-        parameterModel: z.optional(zModelWithString)
+        parameterModel: z._default(z.optional(zModelWithString), {
+            prop: 'Hello World!'
+        })
     }))
 });
 
diff --git a/packages/openapi-ts-tests/zod/v3/__snapshots__/3.1.x/v3/default/zod.gen.ts b/packages/openapi-ts-tests/zod/v3/__snapshots__/3.1.x/v3/default/zod.gen.ts
index 552a53bc63..e56c1943f4 100644
--- a/packages/openapi-ts-tests/zod/v3/__snapshots__/3.1.x/v3/default/zod.gen.ts
+++ b/packages/openapi-ts-tests/zod/v3/__snapshots__/3.1.x/v3/default/zod.gen.ts
@@ -1484,7 +1484,9 @@ export const zCallWithDefaultParametersData = z.object({
             'Error'
         ]).optional(),
         parameterModel: z.union([
-            zModelWithString,
+            zModelWithString.default({
+                prop: 'Hello World!'
+            }),
             z.null()
         ]).optional()
     }).optional()
@@ -1502,7 +1504,9 @@ export const zCallWithDefaultOptionalParametersData = z.object({
             'Warning',
             'Error'
         ]).optional(),
-        parameterModel: zModelWithString.optional()
+        parameterModel: zModelWithString.optional().default({
+            prop: 'Hello World!'
+        })
     }).optional()
 });
 
diff --git a/packages/openapi-ts-tests/zod/v3/__snapshots__/3.1.x/v4/default/zod.gen.ts b/packages/openapi-ts-tests/zod/v3/__snapshots__/3.1.x/v4/default/zod.gen.ts
index 3386046ff7..6279534dbd 100644
--- a/packages/openapi-ts-tests/zod/v3/__snapshots__/3.1.x/v4/default/zod.gen.ts
+++ b/packages/openapi-ts-tests/zod/v3/__snapshots__/3.1.x/v4/default/zod.gen.ts
@@ -1486,7 +1486,9 @@ export const zCallWithDefaultParametersData = z.object({
             'Error'
         ])),
         parameterModel: z.optional(z.union([
-            zModelWithString,
+            zModelWithString.default({
+                prop: 'Hello World!'
+            }),
             z.null()
         ]))
     }))
@@ -1504,7 +1506,9 @@ export const zCallWithDefaultOptionalParametersData = z.object({
             'Warning',
             'Error'
         ])),
-        parameterModel: z.optional(zModelWithString)
+        parameterModel: z.optional(zModelWithString).default({
+            prop: 'Hello World!'
+        })
     }))
 });
 
diff --git a/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/mini/default/zod.gen.ts b/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/mini/default/zod.gen.ts
index 398c91a445..5ffa612787 100644
--- a/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/mini/default/zod.gen.ts
+++ b/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/mini/default/zod.gen.ts
@@ -1486,7 +1486,9 @@ export const zCallWithDefaultParametersData = z.object({
             'Error'
         ])),
         parameterModel: z.optional(z.union([
-            zModelWithString,
+            z._default(zModelWithString, {
+                prop: 'Hello World!'
+            }),
             z.null()
         ]))
     }))
@@ -1504,7 +1506,9 @@ export const zCallWithDefaultOptionalParametersData = z.object({
             'Warning',
             'Error'
         ])),
-        parameterModel: z.optional(zModelWithString)
+        parameterModel: z._default(z.optional(zModelWithString), {
+            prop: 'Hello World!'
+        })
     }))
 });
 
diff --git a/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/mini/defaults-with-ref-and-anyof/zod.gen.ts b/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/mini/defaults-with-ref-and-anyof/zod.gen.ts
new file mode 100644
index 0000000000..74f89f961c
--- /dev/null
+++ b/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/mini/defaults-with-ref-and-anyof/zod.gen.ts
@@ -0,0 +1,40 @@
+// This file is auto-generated by @hey-api/openapi-ts
+
+import * as z from 'zod/mini';
+
+export const zAudioFormat = z.enum([
+    'pcm_16bit_44.1khz',
+    'pcm_16bit_24khz'
+]);
+
+export const zLanguage = z.enum([
+    'en',
+    'es',
+    'fr'
+]);
+
+export const zNestedConfig = z.object({
+    model: z._default(z.string(), 'gpt-4'),
+    temperature: z._default(z.number(), 1)
+});
+
+export const zTestSchema = z.object({
+    primitiveDefault: z._default(z.number(), 42),
+    refWithPrimitiveDefault: z._default(zAudioFormat, 'pcm_16bit_44.1khz'),
+    refWithObjectDefault: z._default(zNestedConfig, {
+        model: 'gpt-4',
+        temperature: 1
+    }),
+    anyOfWithNullDefault: z._default(z.union([
+        z.number(),
+        z.null()
+    ]), null),
+    anyOfWithRefAndNullDefault: z._default(z.union([
+        zLanguage,
+        z.null()
+    ]), null),
+    optionalAnyOfWithDefault: z._default(z.optional(z.union([
+        z.string(),
+        z.null()
+    ])), null)
+});
diff --git a/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v3/default/zod.gen.ts b/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v3/default/zod.gen.ts
index 291c230d83..49aa50ac5d 100644
--- a/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v3/default/zod.gen.ts
+++ b/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v3/default/zod.gen.ts
@@ -1484,7 +1484,9 @@ export const zCallWithDefaultParametersData = z.object({
             'Error'
         ]).optional(),
         parameterModel: z.union([
-            zModelWithString,
+            zModelWithString.default({
+                prop: 'Hello World!'
+            }),
             z.null()
         ]).optional()
     }).optional()
@@ -1502,7 +1504,9 @@ export const zCallWithDefaultOptionalParametersData = z.object({
             'Warning',
             'Error'
         ]).optional(),
-        parameterModel: zModelWithString.optional()
+        parameterModel: zModelWithString.optional().default({
+            prop: 'Hello World!'
+        })
     }).optional()
 });
 
diff --git a/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v3/defaults-with-ref-and-anyof/zod.gen.ts b/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v3/defaults-with-ref-and-anyof/zod.gen.ts
new file mode 100644
index 0000000000..48d5f8925a
--- /dev/null
+++ b/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v3/defaults-with-ref-and-anyof/zod.gen.ts
@@ -0,0 +1,40 @@
+// This file is auto-generated by @hey-api/openapi-ts
+
+import { z } from 'zod/v3';
+
+export const zAudioFormat = z.enum([
+    'pcm_16bit_44.1khz',
+    'pcm_16bit_24khz'
+]);
+
+export const zLanguage = z.enum([
+    'en',
+    'es',
+    'fr'
+]);
+
+export const zNestedConfig = z.object({
+    model: z.string().default('gpt-4'),
+    temperature: z.number().default(1)
+});
+
+export const zTestSchema = z.object({
+    primitiveDefault: z.number().default(42),
+    refWithPrimitiveDefault: zAudioFormat.default('pcm_16bit_44.1khz'),
+    refWithObjectDefault: zNestedConfig.default({
+        model: 'gpt-4',
+        temperature: 1
+    }),
+    anyOfWithNullDefault: z.union([
+        z.number(),
+        z.null()
+    ]).default(null),
+    anyOfWithRefAndNullDefault: z.union([
+        zLanguage,
+        z.null()
+    ]).default(null),
+    optionalAnyOfWithDefault: z.union([
+        z.string(),
+        z.null()
+    ]).optional().default(null)
+});
diff --git a/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v4/default/zod.gen.ts b/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v4/default/zod.gen.ts
index 747685731a..8bafc886b2 100644
--- a/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v4/default/zod.gen.ts
+++ b/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v4/default/zod.gen.ts
@@ -1486,7 +1486,9 @@ export const zCallWithDefaultParametersData = z.object({
             'Error'
         ])),
         parameterModel: z.optional(z.union([
-            zModelWithString,
+            zModelWithString.default({
+                prop: 'Hello World!'
+            }),
             z.null()
         ]))
     }))
@@ -1504,7 +1506,9 @@ export const zCallWithDefaultOptionalParametersData = z.object({
             'Warning',
             'Error'
         ])),
-        parameterModel: z.optional(zModelWithString)
+        parameterModel: z.optional(zModelWithString).default({
+            prop: 'Hello World!'
+        })
     }))
 });
 
diff --git a/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v4/defaults-with-ref-and-anyof/zod.gen.ts b/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v4/defaults-with-ref-and-anyof/zod.gen.ts
new file mode 100644
index 0000000000..6a47287f0c
--- /dev/null
+++ b/packages/openapi-ts-tests/zod/v4/__snapshots__/3.1.x/v4/defaults-with-ref-and-anyof/zod.gen.ts
@@ -0,0 +1,40 @@
+// This file is auto-generated by @hey-api/openapi-ts
+
+import { z } from 'zod';
+
+export const zAudioFormat = z.enum([
+    'pcm_16bit_44.1khz',
+    'pcm_16bit_24khz'
+]);
+
+export const zLanguage = z.enum([
+    'en',
+    'es',
+    'fr'
+]);
+
+export const zNestedConfig = z.object({
+    model: z.string().default('gpt-4'),
+    temperature: z.number().default(1)
+});
+
+export const zTestSchema = z.object({
+    primitiveDefault: z.number().default(42),
+    refWithPrimitiveDefault: zAudioFormat.default('pcm_16bit_44.1khz'),
+    refWithObjectDefault: zNestedConfig.default({
+        model: 'gpt-4',
+        temperature: 1
+    }),
+    anyOfWithNullDefault: z.union([
+        z.number(),
+        z.null()
+    ]).default(null),
+    anyOfWithRefAndNullDefault: z.union([
+        zLanguage,
+        z.null()
+    ]).default(null),
+    optionalAnyOfWithDefault: z.optional(z.union([
+        z.string(),
+        z.null()
+    ])).default(null)
+});
diff --git a/packages/openapi-ts-tests/zod/v4/test/3.1.x.test.ts b/packages/openapi-ts-tests/zod/v4/test/3.1.x.test.ts
index c8d0d0b1c3..03877b95f9 100644
--- a/packages/openapi-ts-tests/zod/v4/test/3.1.x.test.ts
+++ b/packages/openapi-ts-tests/zod/v4/test/3.1.x.test.ts
@@ -42,6 +42,13 @@ for (const zodVersion of zodVersions) {
         description:
           'generates correct array when items are oneOf array with single item',
       },
+      {
+        config: createConfig({
+          input: 'defaults-with-ref-and-anyof.json',
+          output: 'defaults-with-ref-and-anyof',
+        }),
+        description: 'preserves defaults with $ref and anyOf',
+      },
       {
         config: createConfig({
           input: 'enum-null.json',
diff --git a/packages/openapi-ts/src/openApi/3.1.x/parser/schema.ts b/packages/openapi-ts/src/openApi/3.1.x/parser/schema.ts
index 7a270dd398..fb4fbebcba 100644
--- a/packages/openapi-ts/src/openApi/3.1.x/parser/schema.ts
+++ b/packages/openapi-ts/src/openApi/3.1.x/parser/schema.ts
@@ -382,6 +382,7 @@ const parseAllOf = ({
   state: SchemaState;
 }): IR.SchemaObject => {
   let irSchema = initIrSchema({ schema });
+  parseSchemaMeta({ irSchema, schema });
 
   const schemaItems: Array<IR.SchemaObject> = [];
   const schemaTypes = getSchemaTypes({ schema });
@@ -543,6 +544,7 @@ const parseAnyOf = ({
   state: SchemaState;
 }): IR.SchemaObject => {
   let irSchema = initIrSchema({ schema });
+  parseSchemaMeta({ irSchema, schema });
 
   const schemaItems: Array<IR.SchemaObject> = [];
   const schemaTypes = getSchemaTypes({ schema });
@@ -699,6 +701,7 @@ const parseOneOf = ({
   state: SchemaState;
 }): IR.SchemaObject => {
   let irSchema = initIrSchema({ schema });
+  parseSchemaMeta({ irSchema, schema });
 
   let schemaItems: Array<IR.SchemaObject> = [];
   const schemaTypes = getSchemaTypes({ schema });
@@ -817,6 +820,7 @@ const parseRef = ({
   }
 
   let irSchema = initIrSchema({ schema });
+  parseSchemaMeta({ irSchema, schema });
 
   const irRefSchema: IR.SchemaObject = {};
 
diff --git a/specs/3.1.x/defaults-with-ref-and-anyof.json b/specs/3.1.x/defaults-with-ref-and-anyof.json
new file mode 100644
index 0000000000..933e7f08ff
--- /dev/null
+++ b/specs/3.1.x/defaults-with-ref-and-anyof.json
@@ -0,0 +1,76 @@
+{
+  "openapi": "3.1.0",
+  "info": {
+    "title": "Defaults with $ref and anyOf",
+    "version": "1.0.0"
+  },
+  "paths": {},
+  "components": {
+    "schemas": {
+      "AudioFormat": {
+        "type": "string",
+        "enum": ["pcm_16bit_44.1khz", "pcm_16bit_24khz"]
+      },
+      "Language": {
+        "type": "string",
+        "enum": ["en", "es", "fr"]
+      },
+      "NestedConfig": {
+        "type": "object",
+        "properties": {
+          "model": {
+            "type": "string",
+            "default": "gpt-4"
+          },
+          "temperature": {
+            "type": "number",
+            "default": 1
+          }
+        },
+        "required": ["model", "temperature"]
+      },
+      "TestSchema": {
+        "type": "object",
+        "properties": {
+          "primitiveDefault": {
+            "type": "number",
+            "default": 42
+          },
+          "refWithPrimitiveDefault": {
+            "$ref": "#/components/schemas/AudioFormat",
+            "default": "pcm_16bit_44.1khz"
+          },
+          "refWithObjectDefault": {
+            "$ref": "#/components/schemas/NestedConfig",
+            "default": {
+              "model": "gpt-4",
+              "temperature": 1
+            }
+          },
+          "anyOfWithNullDefault": {
+            "anyOf": [{ "type": "number" }, { "type": "null" }],
+            "default": null
+          },
+          "anyOfWithRefAndNullDefault": {
+            "anyOf": [
+              { "$ref": "#/components/schemas/Language" },
+              { "type": "null" }
+            ],
+            "default": null
+          },
+          "optionalAnyOfWithDefault": {
+            "anyOf": [{ "type": "string" }, { "type": "null" }],
+            "default": null
+          }
+        },
+        "required": [
+          "primitiveDefault",
+          "refWithPrimitiveDefault",
+          "refWithObjectDefault",
+          "anyOfWithNullDefault",
+          "anyOfWithRefAndNullDefault"
+        ]
+      }
+    }
+  }
+}