Walsh is one of the original members of Biden's cabinet, and will be the first to leave.
The news comes as Biden prepares for the State of the Union address Tuesday night.
Walsh was a key player in brokering a deal between a railroad worker union and management to avert a massive strike during the holiday season.
Who is Marty Walsh?
Marty Walsh started as mayor of Boston in 2014 and left to join the Biden administration as Secretary of Labor. He is a former union worker who led Laborers Local 223, a construction union, and Boston Building Trades.
Marty Walsh and the railroad strike
What workers want: Congress steps to avert impending rail strike at Biden's ask.
This article originally appeared on USA TODAY: Biden's labor department chief leaving post for job with NHL union