Aside from the new look unveiled Tuesday, Yahoo! introduced email apps for the iPhone, iPad, and mobile devices running on the new Windows 8 operating system.
The company, which is based in Sunnyvale, Calif., also updated its app designed for Google's Android operating system.
As she nears the end of her fifth month on the job, Yahoo! CEO Marissa Mayer is trying to give people more reasons to use the company's online services and stick around longer.
Mayer played a key role in building Google's Gmail, which has emerged as the world's top email service in just eight years.