diff --git a/lib/open_api_spex/cast_parameters.ex b/lib/open_api_spex/cast_parameters.ex
index 1155cb79..bd44fe8b 100644
--- a/lib/open_api_spex/cast_parameters.ex
+++ b/lib/open_api_spex/cast_parameters.ex
@@ -39,7 +39,12 @@ defmodule OpenApiSpex.CastParameters do
   end
 
   defp get_params_by_location(conn, :query, _) do
-    Plug.Conn.fetch_query_params(conn).query_params
+    params = Plug.Conn.fetch_query_params(conn).query_params
+
+    Enum.reduce(params, %{}, fn param, acc ->
+      {updated_key, updated_value} = parse_query_param(param)
+      Map.update(acc, updated_key, updated_value, &[&1 | updated_value])
+    end)
   end
 
   defp get_params_by_location(conn, :path, _) do
@@ -61,6 +66,14 @@ defmodule OpenApiSpex.CastParameters do
         do: {property_name, value}
   end
 
+  defp parse_query_param({key, value}) when is_list(value) do
+    {"#{key}[]", value}
+  end
+
+  defp parse_query_param(param) do
+    param
+  end
+
   defp create_location_schema(parameters, components) do
     {
       %Schema{
diff --git a/test/operation2_test.exs b/test/operation2_test.exs
index 9eeba145..e308b56c 100644
--- a/test/operation2_test.exs
+++ b/test/operation2_test.exs
@@ -50,6 +50,12 @@ defmodule OpenApiSpex.Operation2Test do
     @user_index %Operation{
       operationId: "UserController.index",
       parameters: [
+        Operation.parameter(
+          :"ids[]",
+          :query,
+          %Schema{type: :array, items: %Schema{type: :integer}},
+          "Filter by user ids"
+        ),
         Operation.parameter(:name, :query, :string, "Filter by user name"),
         Operation.parameter(:age, :query, :integer, "Filter by user age"),
         %Reference{"$ref": "#/components/parameters/member"},
@@ -299,13 +305,21 @@ defmodule OpenApiSpex.Operation2Test do
     end
 
     test "casts valid query params and respects defaults" do
-      valid_query_params = %{"name" => "Rubi", "age" => "31", "member" => "true"}
+      valid_query_params = %{"ids[]" => 1, "name" => "Rubi", "age" => "31", "member" => "true"}
       assert {:ok, conn} = do_index_cast(valid_query_params)
-      assert conn.params == %{age: 31, member: true, name: "Rubi", include_archived: false}
+
+      assert conn.params == %{
+               "ids[]": [1],
+               age: 31,
+               member: true,
+               name: "Rubi",
+               include_archived: false
+             }
     end
 
     test "casts valid query params and overrides defaults" do
       valid_query_params = %{
+        "ids[]" => 1,
         "name" => "Rubi",
         "age" => "31",
         "member" => "true",
@@ -313,15 +327,29 @@ defmodule OpenApiSpex.Operation2Test do
       }
 
       assert {:ok, conn} = do_index_cast(valid_query_params)
-      assert conn.params == %{age: 31, member: true, name: "Rubi", include_archived: true}
+
+      assert conn.params == %{
+               "ids[]": [1],
+               age: 31,
+               member: true,
+               name: "Rubi",
+               include_archived: true
+             }
     end
 
     test "cast valid query params with replace_params: false" do
-      valid_query_params = %{"name" => "Rubi", "age" => "31", "member" => "true"}
+      valid_query_params = %{"ids[]" => 1, "name" => "Rubi", "age" => "31", "member" => "true"}
       assert {:ok, conn} = do_index_cast(valid_query_params, replace_params: false)
-      assert Plug.Conn.fetch_query_params(conn).params == valid_query_params
+
+      assert Plug.Conn.fetch_query_params(conn).params == %{
+               "ids" => ["1"],
+               "name" => "Rubi",
+               "age" => "31",
+               "member" => "true"
+             }
 
       assert conn.private.open_api_spex.params == %{
+               "ids[]": [1],
                age: 31,
                member: true,
                name: "Rubi",
@@ -330,9 +358,9 @@ defmodule OpenApiSpex.Operation2Test do
     end
 
     test "casts valid query params without applying defaults" do
-      valid_query_params = %{"name" => "Rubi", "age" => "31", "member" => "true"}
+      valid_query_params = %{"ids[]" => 1, "name" => "Rubi", "age" => "31", "member" => "true"}
       assert {:ok, conn} = do_index_cast(valid_query_params, apply_defaults: false)
-      assert conn.params == %{age: 31, member: true, name: "Rubi"}
+      assert conn.params == %{"ids[]": [1], age: 31, member: true, name: "Rubi"}
     end
 
     test "validate invalid data type for query param" do
diff --git a/test/plug/cast_test.exs b/test/plug/cast_test.exs
index 22b7e78f..2df5cf53 100644
--- a/test/plug/cast_test.exs
+++ b/test/plug/cast_test.exs
@@ -38,6 +38,18 @@ defmodule OpenApiSpex.Plug.CastTest do
       assert OpenApiSpex.params(conn) == %{validParam: true}
     end
 
+    test "ids[] param" do
+      conn =
+        :get
+        |> Plug.Test.conn("/api/users?ids[]=123")
+        |> OpenApiSpexTest.Router.call([])
+
+      assert conn.status == 200
+      assert conn.private.open_api_spex.params == conn.params
+
+      assert OpenApiSpex.params(conn) == %{"ids[]": [123]}
+    end
+
     test "valid param with replace_params false" do
       conn =
         :get
diff --git a/test/support/user_controller.ex b/test/support/user_controller.ex
index b4522f66..6aeb8526 100644
--- a/test/support/user_controller.ex
+++ b/test/support/user_controller.ex
@@ -41,7 +41,13 @@ defmodule OpenApiSpexTest.UserController do
   List all users
   """
   @doc parameters: [
-         validParam: [in: :query, type: :boolean, description: "Valid Param", example: true]
+         validParam: [in: :query, type: :boolean, description: "Valid Param", example: true],
+         "ids[]": [
+           in: :query,
+           type: %Schema{type: :array, items: %Schema{type: :integer}},
+           description: "User IDs",
+           example: 123
+         ]
        ],
        responses: [
          ok: {"User List Response", "application/json", Schemas.UsersResponse}