Santangelo, who will enter his sixth season with MASN, is the fifth TV partner for Carpenter, who has worked with Tom Paciorek, Don Sutton, Rob Dibble and Knight.
"Excited and honored to begin my 16th year in this franchise," Santangelo said on Twitter. "Thank you to the Nats and MASN for making that possible."
Kolko is entering his third year with the Nationals. He is also a contributor on the MLB Network.
"Yup, I will indeed be back as the on-field reporter for Nats broadcasts on MASN next season. Very excited," Kolko said on Twitter.
Holliday, who is known for his play-by-play with Maryland football and basketball, has been the studio host since the Nationals' inaugural season in 2005.