Apply custom master page for Modern SharePoint Site in SharePoint online

Microsoft is ushering its classic collaboration platform into the 21st century with the SharePoint modern pages roll out to make intranet pages mobile-friendly and easier to customize.

Out of Box, SharePoint doesn't provide customizing the master page and changing the master page for the SharePoint Site collection or SharePoint Site.

But, We often come across the need for using a customized master page, owing to various business needs. SharePoint has advanced much in terms of its master page design and deployment and gives much emphasis to non-server side components (HTML5/CSS3, Bootstrap, etc.)

So, This article is a work around and step by step manual on how to create a Master page in SharePoint Modern site using HTML and apply it.

Note: Please try this SharePoint Feature activation in Test environments before activating it in Production or any critical environments.

Step 1 - Select "SiteSettings" Page
"_layouts/15/settings.aspx"

This is the default look of SharePoint Settings before we proceed further

Step 2 - Active "SharePoint Server Publishing Infrastructure" in Site collection Features

a. Click on "Site collection features" under "Site Collection Administration"
b. Activate "SharePoint Server Publishing Infrastructure" feature

It takes some time to activate depends on your internet speed.

Step 3 - After activating "SharePoint Server Publishing Infrastructure" feature navigate back to Site Settings page to Active "SharePoint Server Publishing" in "Manage Site Features"

a. Click on "Manage site features" under "Site Actions"
b. Activate "SharePoint Server Publishing" feature

It takes some time to activate depends on your internet speed.

After activating "SharePoint Server Publishing" feature navigate back to site settings it should look something like this

You can see many old SharePoint features in Site Settings in addition to the "Master Page" and "Page Layouts and Site Templates" for SharePoint Modern Site in SharePoint Online

Hurray..!! now we have provision to change the Master Page.

Note: Please try this (SharePoint Feature activation to get back Master Page Customization for Modern Sites) in Test environments before activating it in Production or any critical environments.