These days most of the user want to use their own master page in SharePoint 2013 Or Office 365. Here we will discuss how to create a custom master page using design manager in SharePoint Online/2013/2016
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Design Manager is SharePoint 2013 is a new feature which can be very useful for SharePoint designers. With SharePoint Design Manger you can now create a custom SharePoint Master Page out of simple Html Page Template in SharePoint 2013/2016 or SharePoint Online.
Here is Master Page that I will use.

The Design Manager is not activated by default in SharePoint 2013/2016 Or in Office 365.
1. Activate the feature “SharePoint Server Publishing Infrastructure” present in the site collection level in SharePoint Online site. This can be navigated as Settings -> Site settings -> Site collection features (under Site Collection Administration) -> SharePoint Server Publishing Infrastructure -> Click on Activate.

2. Once the site collection feature has been activated in the above step, then navigate to the subsite, and activate the Site Feature –> “SharePoint Server Publishing“. This can be navigated as – Settings -> Site settings -> Manage site features (under Site Actions) -> SharePoint Server Publishing -> Click on Activate

3. Now we can see that the Design Manager is activated and is available in Site Settings page. Go to Site Setting -> Look and Feel ->Design Manager

Steps to a custom master page in SharePoint Online/2013/2016 using Design Manager
1. Upload HTML Master Page in Master Page Gallery in SharePoint Online or SharePoint 2013/2016.

2. Add the Required Scripts, CSS, Images and other files.

3. Navigate to Design Manager (Settings- >Look and Feel – > Design Manager)

4. In Design Manager select 4 option Edit Master Pages.

5. Next Select Convert an Html file to a SharePoint master page like below:


6. After following above set you can see that a Html while get convert to master page. Refer below the screen.


7. After master page got generated need to go to Site settings- > Master Page Gallery and need to Publish HTML with major version. Refer below the screen.

8. Finally, we need to apply the new master page (Settings- >Look and Feel – > Design Manager- >Publish and Apply Design – > Assign master page to your site based on device channel.) Refer below screens.

In the Site Master Page Settings page, you can change the System Master page as our new custom master page in SharePoint Online/2013/2016.

Your Final Office 365 (O365) SharePoint Online site screen will look like below:

You may like following SharePoint master page tutorials:
- How to change Master Page in SharePoint 2016, SharePoint 2013 or SharePoint Online?
- Steps to hide quick launch bar in SharePoint online SharePoint 2016/2013
- Convert an HTML page into a SharePoint master page using Design manager in SharePoint serve 2013
- Set master page for a particular page in SharePoint 2016 or SharePoint Online
- SharePoint 2013 Create a custom master page using Visual Studio 2013
- Site Title snippet in SharePoint 2013 custom master page
- Hide master page elements in dialogs in SharePoint 2013
- Creating fixed width master page in SharePoint 2013
- Create a responsive mobile master page using SharePoint 2013 designer
- Change Master Page using PowerShell in SharePoint 2013
- How to appear Developer Dashboard in custom master page in SharePoint?
Hopefully, this sharepoint branding article will help you to create a master page in SharePoint online using design manager. The say way we can create custom master page using designer in SharePoint Online or SharePoint 2013/2016.