diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 2e39633a0..e852e0f25 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -102,6 +102,9 @@ jobs:
             uv.lock
       - name: Install Dependencies
         run: uv sync --no-dev --group tests --extra all
+      - name: Ensure that we have the lowest supported Pydantic version
+        if: matrix.uv-resolution == 'lowest-direct'
+        run: uv pip install "pydantic==2.9.0"
       - name: Install Starlette from source
         if: matrix.starlette-src == 'starlette-git'
         run: uv pip install "git+https://github.com/Kludex/starlette@main"
diff --git a/pyproject.toml b/pyproject.toml
index 73d392929..612d8a0d8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -43,7 +43,7 @@ classifiers = [
 ]
 dependencies = [
     "starlette>=0.46.0",
-    "pydantic>=2.7.0",
+    "pydantic>=2.9.0",
     "typing-extensions>=4.8.0",
     "typing-inspection>=0.4.2",
     "annotated-doc>=0.0.2",
@@ -156,7 +156,7 @@ docs-tests = [
 ]
 github-actions = [
     "httpx >=0.27.0,<1.0.0",
-    "pydantic >=2.5.3,<3.0.0",
+    "pydantic >=2.9.0,<3.0.0",
     "pydantic-settings >=2.1.0,<3.0.0",
     "pygithub >=2.3.0,<3.0.0",
     "pyyaml >=5.3.1,<7.0.0",
diff --git a/tests/test_schema_compat_pydantic_v2.py b/tests/test_schema_compat_pydantic_v2.py
index 737687f25..7612c6ab5 100644
--- a/tests/test_schema_compat_pydantic_v2.py
+++ b/tests/test_schema_compat_pydantic_v2.py
@@ -1,4 +1,5 @@
 import pytest
+from dirty_equals import IsOneOf
 from fastapi import FastAPI
 from fastapi.testclient import TestClient
 from inline_snapshot import snapshot
@@ -63,28 +64,58 @@ def test_openapi_schema(client: TestClient):
                 }
             },
             "components": {
-                "schemas": {
-                    "PlatformRole": {
-                        "type": "string",
-                        "enum": ["admin", "user"],
-                        "title": "PlatformRole",
-                    },
-                    "User": {
-                        "properties": {
-                            "username": {"type": "string", "title": "Username"},
-                            "role": {
-                                "anyOf": [
-                                    {"$ref": "#/components/schemas/PlatformRole"},
-                                    {"enum": [], "title": "OtherRole"},
-                                ],
-                                "title": "Role",
-                            },
+                "schemas": IsOneOf(
+                    # Pydantic >= 2.11: no top-level OtherRole
+                    {
+                        "PlatformRole": {
+                            "type": "string",
+                            "enum": ["admin", "user"],
+                            "title": "PlatformRole",
+                        },
+                        "User": {
+                            "properties": {
+                                "username": {"type": "string", "title": "Username"},
+                                "role": {
+                                    "anyOf": [
+                                        {"$ref": "#/components/schemas/PlatformRole"},
+                                        {"enum": [], "title": "OtherRole"},
+                                    ],
+                                    "title": "Role",
+                                },
+                            },
+                            "type": "object",
+                            "required": ["username", "role"],
+                            "title": "User",
                         },
-                        "type": "object",
-                        "required": ["username", "role"],
-                        "title": "User",
                     },
-                }
+                    # Pydantic < 2.11: adds a top-level OtherRole schema
+                    {
+                        "OtherRole": {
+                            "enum": [],
+                            "title": "OtherRole",
+                        },
+                        "PlatformRole": {
+                            "type": "string",
+                            "enum": ["admin", "user"],
+                            "title": "PlatformRole",
+                        },
+                        "User": {
+                            "properties": {
+                                "username": {"type": "string", "title": "Username"},
+                                "role": {
+                                    "anyOf": [
+                                        {"$ref": "#/components/schemas/PlatformRole"},
+                                        {"enum": [], "title": "OtherRole"},
+                                    ],
+                                    "title": "Role",
+                                },
+                            },
+                            "type": "object",
+                            "required": ["username", "role"],
+                            "title": "User",
+                        },
+                    },
+                )
             },
         }
     )
diff --git a/tests/test_union_body_discriminator.py b/tests/test_union_body_discriminator.py
index 1b682c775..53350abc0 100644
--- a/tests/test_union_body_discriminator.py
+++ b/tests/test_union_body_discriminator.py
@@ -1,5 +1,6 @@
 from typing import Annotated, Any, Literal
 
+from dirty_equals import IsOneOf
 from fastapi import FastAPI
 from fastapi.testclient import TestClient
 from inline_snapshot import snapshot
@@ -88,11 +89,19 @@ def test_discriminator_pydantic_v2() -> None:
                                 "description": "Successful Response",
                                 "content": {
                                     "application/json": {
-                                        "schema": {
-                                            "type": "object",
-                                            "additionalProperties": True,
-                                            "title": "Response Save Union Body Discriminator Items  Post",
-                                        }
+                                        "schema": IsOneOf(
+                                            # Pydantic < 2.11: no additionalProperties
+                                            {
+                                                "type": "object",
+                                                "title": "Response Save Union Body Discriminator Items  Post",
+                                            },
+                                            # Pydantic >= 2.11: has additionalProperties
+                                            {
+                                                "type": "object",
+                                                "additionalProperties": True,
+                                                "title": "Response Save Union Body Discriminator Items  Post",
+                                            },
+                                        )
                                     }
                                 },
                             },
@@ -114,11 +123,21 @@ def test_discriminator_pydantic_v2() -> None:
                 "schemas": {
                     "FirstItem": {
                         "properties": {
-                            "value": {
-                                "type": "string",
-                                "const": "first",
-                                "title": "Value",
-                            },
+                            "value": IsOneOf(
+                                # Pydantic >= 2.10: const only
+                                {
+                                    "type": "string",
+                                    "const": "first",
+                                    "title": "Value",
+                                },
+                                # Pydantic 2.9: const + enum
+                                {
+                                    "type": "string",
+                                    "const": "first",
+                                    "enum": ["first"],
+                                    "title": "Value",
+                                },
+                            ),
                             "price": {"type": "integer", "title": "Price"},
                         },
                         "type": "object",
@@ -140,11 +159,21 @@ def test_discriminator_pydantic_v2() -> None:
                     },
                     "OtherItem": {
                         "properties": {
-                            "value": {
-                                "type": "string",
-                                "const": "other",
-                                "title": "Value",
-                            },
+                            "value": IsOneOf(
+                                # Pydantic >= 2.10.0: const only
+                                {
+                                    "type": "string",
+                                    "const": "other",
+                                    "title": "Value",
+                                },
+                                # Pydantic 2.9.x: const + enum
+                                {
+                                    "type": "string",
+                                    "const": "other",
+                                    "enum": ["other"],
+                                    "title": "Value",
+                                },
+                            ),
                             "price": {"type": "number", "title": "Price"},
                         },
                         "type": "object",
diff --git a/uv.lock b/uv.lock
index 096b0a361..90e9b4e46 100644
--- a/uv.lock
+++ b/uv.lock
@@ -1252,7 +1252,7 @@ requires-dist = [
     { name = "jinja2", marker = "extra == 'all'", specifier = ">=3.1.5" },
     { name = "jinja2", marker = "extra == 'standard'", specifier = ">=3.1.5" },
     { name = "jinja2", marker = "extra == 'standard-no-fastapi-cloud-cli'", specifier = ">=3.1.5" },
-    { name = "pydantic", specifier = ">=2.7.0" },
+    { name = "pydantic", specifier = ">=2.9.0" },
     { name = "pydantic-extra-types", marker = "extra == 'all'", specifier = ">=2.0.0" },
     { name = "pydantic-extra-types", marker = "extra == 'standard'", specifier = ">=2.0.0" },
     { name = "pydantic-extra-types", marker = "extra == 'standard-no-fastapi-cloud-cli'", specifier = ">=2.0.0" },
@@ -1350,7 +1350,7 @@ docs-tests = [
 ]
 github-actions = [
     { name = "httpx", specifier = ">=0.27.0,<1.0.0" },
-    { name = "pydantic", specifier = ">=2.5.3,<3.0.0" },
+    { name = "pydantic", specifier = ">=2.9.0,<3.0.0" },
     { name = "pydantic-settings", specifier = ">=2.1.0,<3.0.0" },
     { name = "pygithub", specifier = ">=2.3.0,<3.0.0" },
     { name = "pyyaml", specifier = ">=5.3.1,<7.0.0" },