How to Create a Custom Admin Theme in Magento 2

Magento's admin uses its own theme, Magento/backend. You can create a child admin theme to change branding, colours or layout details — useful for agencies and multi-brand businesses. For small changes, though, a module with a few layout tweaks is often simpler to maintain.

Step 1: Register the Admin Theme

<?php
declare(strict_types=1);

use Magento\Framework\Component\ComponentRegistrar;

ComponentRegistrar::register(
    ComponentRegistrar::THEME,
    'adminhtml/MageServices/backend',
    __DIR__
);

<?xml version="1.0"?>
<theme xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:noNamespaceSchemaLocation="urn:magento:framework:Config/etc/theme.xsd">
    <title>MageServices Backend</title>
    <parent>Magento/backend</parent>
</theme>

Step 2: Apply the Theme With a Module

Admin themes are not selected in the admin. A module tells Magento to use your theme through di.xml:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Theme\Model\View\Design">
        <arguments>
            <argument name="themes" xsi:type="array">
                <item name="adminhtml" xsi:type="string">MageServices/backend</item>
            </argument>
        </arguments>
    </type>
</config>

Add Magento_Theme to the module's <sequence> in module.xml so your configuration loads after it.

Step 3: Override Styles

Admin styles are built with LESS. Add your changes in web/css/source/_theme.less — for example, a brand colour for primary buttons:

// app/design/adminhtml/MageServices/backend/web/css/source/_theme.less
@color-brand: #E8440A;

.action-primary,
.page-actions .page-actions-buttons > button.action-primary {
    background-color: @color-brand;
    border-color: darken(@color-brand, 8%);
}

Step 4: Replace the Admin Logo

Override the logo images in your theme, keeping the same file names as the parent theme so templates pick them up:

app/design/adminhtml/MageServices/backend/web/images/magento-logo.svg
app/design/adminhtml/MageServices/backend/web/images/magento-icon.svg

Step 5: Deploy

bin/magento setup:upgrade
bin/magento setup:static-content:deploy -f --area adminhtml
bin/magento cache:flush

Keep It Light

• Every admin override must be checked after Magento upgrades. Change as little as possible.
• Do not hide or restyle security-related admin features.
• For a different logo on the login page only, a small layout override in a module is often enough.

Changing the Admin Login Page Only

Many merchants only want their own logo on the admin login screen. That does not need a full admin theme. In a module, add view/adminhtml/layout/admin_login.xml and set the logo through the existing block's arguments, or reference the login container and add a small block with your own template. Because this touches one layout handle, it is far less likely to break during upgrades than a theme that overrides many templates.

Debugging Admin Theme Issues

• Theme not applied — confirm the module containing the di.xml is enabled and that setup:upgrade registered the theme in the theme table with area adminhtml.
• Styles not updating — delete pub/static/adminhtml and var/view_preprocessed in developer mode, then redeploy static content.
• Broken admin after upgrade — temporarily remove the di.xml theme argument to fall back to Magento/backend, then review your overrides against the new core files.

If your goal is a better admin experience for your team — faster product editing, custom grids or bulk tools — consider building admin features with UI components instead of restyling the whole admin.

Frequently Asked Questions

Can I choose the admin theme in Content > Design?

No. Admin themes are applied through di.xml in a module, not through the design configuration screen.

Will my admin theme survive upgrades?

Usually, if you only override a few styles and images. Template overrides need review after each upgrade.