diff --git a/packages/docusaurus-theme-classic/package.json b/packages/docusaurus-theme-classic/package.json
index c0167d8f9073..5255b67606bc 100644
--- a/packages/docusaurus-theme-classic/package.json
+++ b/packages/docusaurus-theme-classic/package.json
@@ -20,6 +20,7 @@
     "clsx": "^1.1.1",
     "copy-text-to-clipboard": "^2.2.0",
     "infima": "0.2.0-alpha.12",
+    "lodash": "^4.17.19",
     "parse-numeric-range": "^0.0.2",
     "prism-react-renderer": "^1.1.0",
     "prismjs": "^1.20.0",
diff --git a/packages/docusaurus-theme-classic/src/__tests__/validateThemeConfig.test.js b/packages/docusaurus-theme-classic/src/__tests__/validateThemeConfig.test.js
new file mode 100644
index 000000000000..44531fe179c9
--- /dev/null
+++ b/packages/docusaurus-theme-classic/src/__tests__/validateThemeConfig.test.js
@@ -0,0 +1,86 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+import merge from 'lodash/merge';
+
+const {
+  validateThemeConfig,
+  DEFAULT_COLOR_MODE_CONFIG,
+} = require('../validateThemeConfig');
+
+const mergeDefault = (config) => merge({}, DEFAULT_COLOR_MODE_CONFIG, config);
+
+function testValidateThemeConfig(themeConfig) {
+  function validate(schema, cfg) {
+    const {value, error} = schema.validate(cfg, {
+      convert: false,
+    });
+    if (error) {
+      throw error;
+    }
+    return value;
+  }
+
+  return validateThemeConfig({themeConfig, validate});
+}
+
+describe('color mode config', () => {
+  test('minimal config', () => {
+    const colorMode = {
+      switchConfig: {
+        darkIcon: '🌙',
+      },
+    };
+    expect(testValidateThemeConfig({colorMode})).toEqual({
+      colorMode: mergeDefault(colorMode),
+    });
+  });
+
+  test('max config', () => {
+    const colorMode = {
+      defaultMode: 'dark',
+      disableSwitch: false,
+      respectPrefersColorScheme: true,
+      switchConfig: {
+        darkIcon: '🌙',
+        darkIconStyle: {
+          marginTop: '1px',
+          marginLeft: '2px',
+        },
+        lightIcon: '☀️',
+        lightIconStyle: {
+          marginLeft: '1px',
+        },
+      },
+    };
+    expect(testValidateThemeConfig({colorMode})).toEqual({
+      colorMode: mergeDefault(colorMode),
+    });
+  });
+
+  test('undefined config', () => {
+    const colorMode = undefined;
+    expect(testValidateThemeConfig({colorMode})).toEqual({
+      colorMode: mergeDefault(colorMode),
+    });
+  });
+
+  test('empty config', () => {
+    const colorMode = {};
+    expect(testValidateThemeConfig({colorMode})).toEqual({
+      colorMode: mergeDefault(colorMode),
+    });
+  });
+
+  test('empty switch config', () => {
+    const colorMode = {
+      switchConfig: {},
+    };
+    expect(testValidateThemeConfig({colorMode})).toEqual({
+      colorMode: mergeDefault(colorMode),
+    });
+  });
+});
diff --git a/packages/docusaurus-theme-classic/src/index.js b/packages/docusaurus-theme-classic/src/index.js
index cff72869155f..8d0653830b34 100644
--- a/packages/docusaurus-theme-classic/src/index.js
+++ b/packages/docusaurus-theme-classic/src/index.js
@@ -7,7 +7,7 @@
 
 const path = require('path');
 const Module = require('module');
-const ThemeConfigSchema = require('./themeConfigSchema');
+const {validateThemeConfig} = require('./validateThemeConfig');
 
 const createRequire = Module.createRequire || Module.createRequireFromPath;
 const requireFromDocusaurusCore = createRequire(
@@ -120,6 +120,4 @@ module.exports = function (context, options) {
   };
 };
 
-module.exports.validateThemeConfig = ({validate, themeConfig}) => {
-  return validate(ThemeConfigSchema, themeConfig);
-};
+module.exports.validateThemeConfig = validateThemeConfig;
diff --git a/packages/docusaurus-theme-classic/src/theme/Toggle/index.tsx b/packages/docusaurus-theme-classic/src/theme/Toggle/index.tsx
index a73e95e05551..3ab914e4a242 100644
--- a/packages/docusaurus-theme-classic/src/theme/Toggle/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/Toggle/index.tsx
@@ -13,17 +13,40 @@ import useDocusaurusContext from '@docusaurus/useDocusaurusContext';
 import clsx from 'clsx';
 import styles from './styles.module.css';
 
-const Moon = () => <span className={clsx(styles.toggle, styles.moon)} />;
-const Sun = () => <span className={clsx(styles.toggle, styles.sun)} />;
+const Dark = ({icon, style}) => (
+  <span className={clsx(styles.toggle, styles.dark)} style={style}>
+    {icon}
+  </span>
+);
+const Light = ({icon, style}) => (
+  <span className={clsx(styles.toggle, styles.light)} style={style}>
+    {icon}
+  </span>
+);
 
 export default function (props: ComponentProps<typeof Toggle>): JSX.Element {
-  const {isClient} = useDocusaurusContext();
+  const {
+    siteConfig: {
+      themeConfig: {
+        colorMode: {
+          switchConfig: {
+            darkIcon,
+            darkIconStyle,
+            lightIcon,
+            lightIconStyle,
+          },
+        },
+      },
+    }, 
+    isClient 
+  } = useDocusaurusContext();
+
   return (
     <Toggle
       disabled={!isClient}
       icons={{
-        checked: <Moon />,
-        unchecked: <Sun />,
+        checked: <Dark icon={darkIcon} style={darkIconStyle} />,
+        unchecked: <Light icon={lightIcon} style={lightIconStyle} />,
       }}
       {...props}
     />
diff --git a/packages/docusaurus-theme-classic/src/theme/Toggle/styles.module.css b/packages/docusaurus-theme-classic/src/theme/Toggle/styles.module.css
index 42619f0251f6..1ac128ce8cf1 100644
--- a/packages/docusaurus-theme-classic/src/theme/Toggle/styles.module.css
+++ b/packages/docusaurus-theme-classic/src/theme/Toggle/styles.module.css
@@ -16,12 +16,6 @@
 .toggle::before {
   position: absolute;
 }
-.moon::before {
-  content: '\1F31C';
-}
-.sun::before {
-  content: '\1F31E';
-}
 
 /**
  * styles for React Toggle
diff --git a/packages/docusaurus-theme-classic/src/themeConfigSchema.js b/packages/docusaurus-theme-classic/src/validateThemeConfig.js
similarity index 81%
rename from packages/docusaurus-theme-classic/src/themeConfigSchema.js
rename to packages/docusaurus-theme-classic/src/validateThemeConfig.js
index 7f847f4d6ca1..9cfe86602c87 100644
--- a/packages/docusaurus-theme-classic/src/themeConfigSchema.js
+++ b/packages/docusaurus-theme-classic/src/validateThemeConfig.js
@@ -7,6 +7,19 @@
 
 const Joi = require('@hapi/joi');
 
+const DEFAULT_COLOR_MODE_CONFIG = {
+  defaultMode: 'light',
+  disableSwitch: false,
+  respectPrefersColorScheme: false,
+  switchConfig: {
+    darkIcon: '🌜',
+    darkIconStyle: {},
+    lightIcon: '🌞',
+    lightIconStyle: {},
+  },
+};
+exports.DEFAULT_COLOR_MODE_CONFIG = DEFAULT_COLOR_MODE_CONFIG;
+
 const NavbarItemPosition = Joi.string().equal('left', 'right').default('left');
 
 // TODO we should probably create a custom navbar item type "dropdown"
@@ -102,14 +115,28 @@ const NavbarItemSchema = Joi.object().when('type', {
  */
 
 const ColorModeSchema = Joi.object({
-  defaultMode: Joi.string().equal('dark', 'light').default('light'),
-  disableSwitch: Joi.bool().default(false),
-  respectPrefersColorScheme: Joi.bool().default(false),
-}).default({
-  defaultMode: 'light',
-  disableSwitch: false,
-  respectPrefersColorScheme: false,
-});
+  defaultMode: Joi.string()
+    .equal('dark', 'light')
+    .default(DEFAULT_COLOR_MODE_CONFIG.defaultMode),
+  disableSwitch: Joi.bool().default(DEFAULT_COLOR_MODE_CONFIG.disableSwitch),
+  respectPrefersColorScheme: Joi.bool().default(
+    DEFAULT_COLOR_MODE_CONFIG.respectPrefersColorScheme,
+  ),
+  switchConfig: Joi.object({
+    darkIcon: Joi.string().default(
+      DEFAULT_COLOR_MODE_CONFIG.switchConfig.darkIcon,
+    ),
+    darkIconStyle: Joi.object().default(
+      DEFAULT_COLOR_MODE_CONFIG.switchConfig.darkIconStyle,
+    ),
+    lightIcon: Joi.string().default(
+      DEFAULT_COLOR_MODE_CONFIG.switchConfig.lightIcon,
+    ),
+    lightIconStyle: Joi.object().default(
+      DEFAULT_COLOR_MODE_CONFIG.switchConfig.lightIconStyle,
+    ),
+  }).default(DEFAULT_COLOR_MODE_CONFIG.switchConfig),
+}).default(DEFAULT_COLOR_MODE_CONFIG);
 
 const FooterLinkItemSchema = Joi.object({
   to: Joi.string(),
@@ -178,4 +205,6 @@ const ThemeConfigSchema = Joi.object({
   }),
 });
 
-module.exports = ThemeConfigSchema;
+exports.validateThemeConfig = ({validate, themeConfig}) => {
+  return validate(ThemeConfigSchema, themeConfig);
+};
diff --git a/website/docs/docusaurus.config.js.md b/website/docs/docusaurus.config.js.md
index e15c83d4d124..20a0914c822a 100644
--- a/website/docs/docusaurus.config.js.md
+++ b/website/docs/docusaurus.config.js.md
@@ -158,6 +158,22 @@ Example:
 ```js title="docusaurus.config.js"
 module.exports = {
   themeConfig: {
+    colorMode: {
+      defaultMode: 'light',
+      disableSwitch: false,
+      respectPrefersColorScheme: true,
+      switchConfig: {
+        darkIcon: '🌙',
+        darkIconStyle: { // Style object passed to inline CSS
+        // For more information about styling options visit: https://reactjs.org/docs/dom-elements.html#style
+          marginLeft: '2px',
+        },
+        lightIcon: '\u2600',
+        lightIconStyle: {
+          marginLeft: '1px',
+        },
+      },
+    },
     navbar: {
       title: 'Site Title',
       logo: {