diff --git a/aiohttp_apispec/aiohttp_apispec.py b/aiohttp_apispec/aiohttp_apispec.py
index e96e5bd..cd27266 100644
--- a/aiohttp_apispec/aiohttp_apispec.py
+++ b/aiohttp_apispec/aiohttp_apispec.py
@@ -1,8 +1,10 @@
 import copy
+import enum
+import json
 import os
 from pathlib import Path
-from typing import Awaitable, Callable
-import json
+from typing import Awaitable, Callable, Union
+
 from aiohttp import web
 from aiohttp.hdrs import METH_ALL, METH_ANY
 from apispec import APISpec
@@ -36,6 +38,14 @@ def resolver(schema):
     return name
 
 
+class OpenApiVersion(str, enum.Enum):
+    V20 = "2.0"
+    V300 = "3.0.0"
+    V301 = "3.0.1"
+    V302 = "3.0.2"
+    V303 = "3.0.3"
+
+
 class AiohttpApiSpec:
     def __init__(
         self,
@@ -48,11 +58,23 @@ def __init__(
         in_place=False,
         prefix='',
         schema_name_resolver=resolver,
+        openapi_version=None,
         **kwargs,
     ):
+        openapi_version = openapi_version or OpenApiVersion.V20
+        try:
+            openapi_version = OpenApiVersion(openapi_version)
+        except ValueError:
+            raise ValueError(
+                f"Invalid `openapi_version`: {openapi_version!r}"
+            ) from None
 
         self.plugin = MarshmallowPlugin(schema_name_resolver=schema_name_resolver)
-        self.spec = APISpec(plugins=(self.plugin,), openapi_version="2.0", **kwargs)
+        self.spec = APISpec(
+            plugins=(self.plugin,),
+            openapi_version=openapi_version.value,
+            **kwargs,
+        )
 
         self.url = url
         self.swagger_path = swagger_path
@@ -200,7 +222,14 @@ def _update_paths(self, data: dict, method: str, url_path: str):
                         for k, v in raw_parameters.items()
                         if k in VALID_RESPONSE_FIELDS
                     }
-                    updated_params['schema'] = actual_params["schema"]
+                    if self.spec.components.openapi_version.major < 3:
+                        updated_params['schema'] = actual_params["schema"]
+                    else:
+                        updated_params["content"] = {
+                            "application/json": {
+                                "schema": actual_params["schema"],
+                            },
+                        }
                     for extra_info in ("description", "headers", "examples"):
                         if extra_info in actual_params:
                             updated_params[extra_info] = actual_params[extra_info]
@@ -247,6 +276,7 @@ def setup_aiohttp_apispec(
     in_place: bool = False,
     prefix: str = '',
     schema_name_resolver: Callable = resolver,
+    openapi_version: Union[str, OpenApiVersion] = OpenApiVersion.V20,
     **kwargs,
 ) -> AiohttpApiSpec:
     """
@@ -304,6 +334,7 @@ async def index(request):
                      If True, be sure all routes are added to router
     :param prefix: prefix to add to all registered routes
     :param schema_name_resolver: custom schema_name_resolver for MarshmallowPlugin.
+    :param openapi_version: version of OpenAPI schema
     :param kwargs: any apispec.APISpec kwargs
     :return: return instance of AiohttpApiSpec class
     :rtype: AiohttpApiSpec
@@ -320,5 +351,6 @@ async def index(request):
         in_place=in_place,
         prefix=prefix,
         schema_name_resolver=schema_name_resolver,
+        openapi_version=openapi_version,
         **kwargs,
     )