The search engine announced the closure in an email to Mash's members and advised web users to save any data posted on the site they wish to keep.
Mash was launched in September last year as Yahoo's answer to Facebook and MySpace. It differed from other social networking sites by allowing users to edit each others' profile pages and change the layout of their friend's pages.
Once the service has closed, links to Mash will be redirected to Yahoo's website. The company confirmed its other services such as Yahoo 360 will not be affected by the closure.