He first worked with the Knicks as a radio announcer for WFAN from 1992–97, when he was promoted to television play-by-play upon Marv Albert's firing following his infamous sex scandal. He later became Albert's backup upon his return in 1999, before finally becoming the lead play-by-play upon Albert's second dismissal in 2004. On February 8, 2006, with the departure of Al Michaels from the network, ABC announced that Breen would take over as the lead broadcaster for the NBA, including the NBA Finals. His broadcasting career started doing play-by-play for the Marist College Red Foxes basketball team in 1985. Other than his role as ABC's main play-by-play on Saturday nights, Breen usually works for ESPN on Fridays and occasionally on Wednesdays, usually calling games alongside Mark Jackson and Jeff Van Gundy, with the rest of his schedule reserved for MSG. He has also called college basketball games for ESPN.