Add a watermark in Excel
Microsoft Excel doesn’t come with a built-in watermark button. But you can use an image, like a logo, to create a watermark.
Create a watermark
Select Insert > Header & Footer.
Tap on the header and select Picture.
Insert your image. In the header, you’ll see & Picture.
Tap anywhere outside the header to see the watermark.
Select Picture > Color > Washout to change the look of the image. Grayscale may also work well.
Edit the watermark
Tap back into the header. Select Format Picture under the Design tab.
Select OK to apply the settings.
This feature is not available in Excel Online.
If you have the Excel desktop application, you can use the Open in Excel button to open the workbook and add a watermark.