This article explains two ways to add an image to your Gmail signature. Instructions apply to the desktop version of Gmail on all operating systems.
Gmail makes it easy to add an image to your email signature. You can upload an image from your computer, use an image from a URL, or add a photo you've uploaded to your Google Drive account.
Adding an image to your Gmail signature is as simple as choosing the photo and deciding where you want to place it.
With Gmail open, go to the top right corner and select the Settings (gear) icon. Then from the menu, choose View all settings.