WordPress Multisite lets you run multiple WordPress sites from a single installation – one codebase, one database (with separate tables per site), and one set of plugins and themes managed centrally. It is built into WordPress core and requires no additional plugin to enable. When to use it: for a network of related sites that share themes, plugins, and admin management. When to avoid it: for unrelated client sites where a single point of failure (one compromised installation affecting all sites) is unacceptable.
Before You Enable Multisite
Multisite changes your WordPress installation fundamentally. Back up the database and files before proceeding. Enabling Multisite disables some plugins that are not Multisite-compatible. Test on a staging environment before enabling on a production site. Once enabled, removing Multisite (reverting to a single site) requires manual database work.
Your hosting must support either subdomains (sub1.yoursite.com) or subdirectories (yoursite.com/sub1) for the additional sites. Wildcard subdomain configuration requires server access to add a wildcard DNS record and wildcard SSL certificate. Subdirectory setup is simpler and works on most hosts.
Step 1: Enable Multisite in wp-config.php
Add this line to wp-config.php above the “That’s all, stop editing!” line:
define( 'WP_ALLOW_MULTISITE', true );Save the file. Log back into WordPress admin. A new menu item appears: Tools -> Network Setup.
Need help optimising your WordPress site? Describe your project and get a free estimate.
Step 2: Choose Network Structure
Go to Tools -> Network Setup. Choose between:
- Sub-domains – each site gets a subdomain: site1.yournetwork.com, site2.yournetwork.com. Requires wildcard DNS and SSL. Better for sites that need to appear as separate entities.
- Sub-directories – each site gets a subdirectory: yournetwork.com/site1, yournetwork.com/site2. Simpler setup, works on most shared hosting. Better for sections of the same brand.
Enter your network title and admin email. Click Install. WordPress shows you two code blocks to add to your files.
Step 3: Update wp-config.php and .htaccess
WordPress shows the exact code to add. Copy and paste it precisely:
In wp-config.php (replace the WP_ALLOW_MULTISITE line with the new block):
define( 'MULTISITE', true );
define( 'SUBDOMAIN_INSTALL', false ); // true for subdomains
define( 'DOMAIN_CURRENT_SITE', 'yoursite.com' );
define( 'PATH_CURRENT_SITE', '/' );
define( 'SITE_ID_CURRENT_SITE', 1 );
define( 'BLOG_ID_CURRENT_SITE', 1 );In .htaccess, replace the existing WordPress rules with the Multisite rules WordPress shows you. They are longer than the standard single-site rules.
After saving both files, log out and log back in. The admin now shows a “My Sites” menu in the admin bar and a Network Admin area.
Step 4: Add Sites to the Network
Go to Network Admin -> Sites -> Add New. Enter the site address (the subdomain or subdirectory path), site title, and admin email. WordPress creates the site with its own set of database tables. The site admin can log in and manage their site independently while you manage themes and plugins at the network level.
Managing Plugins and Themes
In Multisite, plugins are installed at the network level and can be: Network Activated (active on all sites automatically), or available for individual site admins to activate. Go to Network Admin -> Plugins to network-activate or deactivate plugins. Themes work similarly – install at the network level and enable per site or network-wide.
Some plugins are not Multisite-compatible and will either not work or need to be network-activated only. Check a plugin’s documentation before installing it on a Multisite network.
Real Use Cases Where Multisite Makes Sense
Multisite genuinely solves specific problems better than separate installations. A university running department sites (arts.university.edu, science.university.edu, engineering.university.edu) benefits from Multisite: one WordPress to update, one theme to maintain, and a central network admin managing all departments. Students and faculty get individual blog spaces (student.university.edu/username) without separate hosting accounts.
A media company running a network of niche publications (food, travel, lifestyle) uses Multisite to share the subscription system, user accounts, and advertising management across all publications while each publication maintains its own editorial independence and visual identity.
A franchise business running location-specific sites (london.franchise.com, manchester.franchise.com, birmingham.franchise.com) uses Multisite to push brand updates, legal notices, and shared content to all locations simultaneously while each location manages its own local events and team pages.
These are the scenarios where Multisite overhead is justified. A web agency running client sites on Multisite is not one of them.