Tuesday's announcement comes after Sharpton spent several weeks as a tryout in the 6 p.m. Eastern time slot.
His new program, to be called "PoliticsNation," will premiere next Monday.
Sharpton is a well-known civil rights activist and minister. He calls the hosting job "a natural extension of my life work and growth."
In addition to being a guest on MSNBC throughout the network's history, he has also served as an occasional guest host on several of its programs. He hosts a nationally syndicated radio show, as well.
The 6 p.m. hour serves as an important lead-in to MSNBC's weeknight slate that includes Chris Matthews, Laurence O'Donnell, Rachel Maddow and Ed Schultz.