diff --git a/changelog_unreleased/api/pr-8890.md b/changelog_unreleased/api/pr-8890.md
index ab1882f93..9bcfeb182 100644
--- a/changelog_unreleased/api/pr-8890.md
+++ b/changelog_unreleased/api/pr-8890.md
@@ -1,3 +1,7 @@
-#### Support `.prettierrc.cjs` and `prettier.config.cjs` config file ([#8890](https://github.com/prettier/prettier/pull/8890) by [@fisker](https://github.com/fisker))
+#### Support `.cjs` and `.json5` configuration files ([#8890](https://github.com/prettier/prettier/pull/8890), [#8957](https://github.com/prettier/prettier/pull/8957) by [@fisker](https://github.com/fisker))
 
-New config files `.prettierrc.cjs` and `prettier.config.cjs` are supported.
+Added new format of configuration files:
+
+- `.prettierrc.json5`
+- `.prettierrc.cjs`
+- `prettier.config.cjs`
diff --git a/docs/configuration.md b/docs/configuration.md
index e60f00cd4..ca89213f0 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -7,7 +7,7 @@ Prettier uses [cosmiconfig](https://github.com/davidtheclark/cosmiconfig) for co
 
 - A `"prettier"` key in your `package.json` file.
 - A `.prettierrc` file written in JSON or YAML.
-- A `.prettierrc.json`, `.prettierrc.yml`, or `.prettierrc.yaml` file.
+- A `.prettierrc.json`, `.prettierrc.yml`, `.prettierrc.yaml`, or `.prettierrc.json5` file.
 - A `.prettierrc.js`, `.prettierrc.cjs`, `prettier.config.js`, or `prettier.config.cjs` file that exports an object using `module.exports`.
 - A `.prettierrc.toml` file.
 
diff --git a/package.json b/package.json
index 3b87c3383..b394175fe 100644
--- a/package.json
+++ b/package.json
@@ -52,6 +52,7 @@
     "html-void-elements": "1.0.5",
     "ignore": "4.0.6",
     "jest-docblock": "26.0.0",
+    "json5": "2.1.3",
     "leven": "3.1.0",
     "lines-and-columns": "1.1.6",
     "linguist-languages": "7.10.0",
diff --git a/src/config/resolve-config.js b/src/config/resolve-config.js
index ca7bbf1ea..090be9b15 100644
--- a/src/config/resolve-config.js
+++ b/src/config/resolve-config.js
@@ -6,6 +6,7 @@ const mem = require("mem");
 const thirdParty = require("../common/third-party");
 
 const loadToml = require("../utils/load-toml");
+const loadJson5 = require("../utils/load-json5");
 const resolve = require("../common/resolve");
 const resolveEditorConfig = require("./resolve-config-editorconfig");
 
@@ -39,6 +40,7 @@ const getExplorerMemoized = mem(
         ".prettierrc.json",
         ".prettierrc.yaml",
         ".prettierrc.yml",
+        ".prettierrc.json5",
         ".prettierrc.js",
         ".prettierrc.cjs",
         "prettier.config.js",
@@ -47,6 +49,7 @@ const getExplorerMemoized = mem(
       ],
       loaders: {
         ".toml": loadToml,
+        ".json5": loadJson5,
       },
     });
 
diff --git a/src/utils/load-json5.js b/src/utils/load-json5.js
new file mode 100644
index 000000000..126aaf64c
--- /dev/null
+++ b/src/utils/load-json5.js
@@ -0,0 +1,12 @@
+"use strict";
+
+const { parse } = require("json5");
+
+module.exports = function (filePath, content) {
+  try {
+    return parse(content);
+  } catch (error) {
+    error.message = `JSON5 Error in ${filePath}:\n${error.message}`;
+    throw error;
+  }
+};
diff --git a/tests_integration/__tests__/config-resolution.js b/tests_integration/__tests__/config-resolution.js
index 872fa89f7..bea830899 100644
--- a/tests_integration/__tests__/config-resolution.js
+++ b/tests_integration/__tests__/config-resolution.js
@@ -308,3 +308,27 @@ test(".cjs config file", async () => {
     await expect(prettier.resolveConfig(file)).resolves.toMatchObject(config);
   }
 });
+
+test(".json5 config file", async () => {
+  const parentDirectory = path.join(__dirname, "../cli/config/rc-json5");
+  const config = {
+    trailingComma: "all",
+    printWidth: 81,
+    tabWidth: 3,
+  };
+  const file = path.join(parentDirectory, "json5/foo.js");
+
+  expect(prettier.resolveConfig.sync(file)).toEqual(config);
+  await expect(prettier.resolveConfig(file)).resolves.toMatchObject(config);
+});
+
+test(".json5 config file(invalid)", async () => {
+  const parentDirectory = path.join(__dirname, "../cli/config/rc-json5");
+  const file = path.join(parentDirectory, "invalid/foo.js");
+  const error = /JSON5: invalid end of input at 2:1/;
+
+  expect(() => {
+    prettier.resolveConfig.sync(file);
+  }).toThrowError(error);
+  await expect(prettier.resolveConfig(file)).rejects.toThrow(error);
+});
diff --git a/tests_integration/cli/config/rc-json5/invalid/.prettierrc.json5 b/tests_integration/cli/config/rc-json5/invalid/.prettierrc.json5
new file mode 100644
index 000000000..98232c64f
--- /dev/null
+++ b/tests_integration/cli/config/rc-json5/invalid/.prettierrc.json5
@@ -0,0 +1 @@
+{
diff --git a/tests_integration/cli/config/rc-json5/json5/.prettierrc.json5 b/tests_integration/cli/config/rc-json5/json5/.prettierrc.json5
new file mode 100644
index 000000000..8cdc1a362
--- /dev/null
+++ b/tests_integration/cli/config/rc-json5/json5/.prettierrc.json5
@@ -0,0 +1,6 @@
+{
+// comment
+  trailingComma: 'all',
+          printWidth: +81,
+  tabWidth: 3.,
+}
diff --git a/yarn.lock b/yarn.lock
index 4430facc2..f890e7f8f 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -5309,6 +5309,13 @@ json-stringify-safe@~5.0.1:
   resolved "https://registry.yarnpkg.com/json-stringify-safe/-/json-stringify-safe-5.0.1.tgz#1296a2d58fd45f19a0f6ce01d65701e2c735b6eb"
   integrity sha1-Epai1Y/UXxmg9s4B1lcB4sc1tus=
 
+json5@2.1.3, json5@^2.1.2:
+  version "2.1.3"
+  resolved "https://registry.yarnpkg.com/json5/-/json5-2.1.3.tgz#c9b0f7fa9233bfe5807fe66fcf3a5617ed597d43"
+  integrity sha512-KXPvOm8K9IJKFM0bmdn8QXh7udDh1g/giieX0NLCaMnb4hEiVFqnop2ImTXCc5e0/oHz3LTqmHGtExn5hfMkOA==
+  dependencies:
+    minimist "^1.2.5"
+
 json5@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/json5/-/json5-1.0.1.tgz#779fb0018604fa854eacbf6252180d83543e3dbe"
@@ -5316,13 +5323,6 @@ json5@^1.0.1:
   dependencies:
     minimist "^1.2.0"
 
-json5@^2.1.2:
-  version "2.1.3"
-  resolved "https://registry.yarnpkg.com/json5/-/json5-2.1.3.tgz#c9b0f7fa9233bfe5807fe66fcf3a5617ed597d43"
-  integrity sha512-KXPvOm8K9IJKFM0bmdn8QXh7udDh1g/giieX0NLCaMnb4hEiVFqnop2ImTXCc5e0/oHz3LTqmHGtExn5hfMkOA==
-  dependencies:
-    minimist "^1.2.5"
-
 jsonfile@^6.0.1:
   version "6.0.1"
   resolved "https://registry.yarnpkg.com/jsonfile/-/jsonfile-6.0.1.tgz#98966cba214378c8c84b82e085907b40bf614179"