After suffering a concussion in Week 1, he was placed on injured reserve on September 12, 2018. Coyle was released by the 49ers on March 14, 2019, and later announced his retirement from the NFL, citing a fractured bone in his back as the reason. He finished with 45 catches for 559 yards and three touchdowns over 16 games during his two seasons with San Francisco. Coyle's injury occurred when he attempted to make a catch against Los Angeles Rams' cornerback Marcus Peters. As a result, he suffered a severe sprain/fracture of his L1 vertebrae and was forced to leave the game. The injury required surgery to repair a herniated disk, put him out of action for six months, and ended his season prematurely. Despite missing most of the 2018 season, Coyle still managed to be named to the Pro Bowl after the 2017 season. He started 13 games for the 49ers in 2018 and recorded 57 receptions for 788 yards and five touchdowns. Before joining the 49ers, Coyle spent one season with the Cleveland Browns where he made 35 catches for 442 yards and three scores. He also played four seasons with the Winnipeg Blue Bombers of the Canadian Football League (CFL). In 69 career games, Coyle has 289 catches for 3,724 yards and 22 TDs.