Ryan was selected by the San Jose Sharks in the seventh round (No. 198) in the 2012 NHL Draft after he had 17 points (seven goals, 10 assists) in 34 games as a freshman for Cornell of the Eastern College Athletic Conference. He played the next three seasons with Cornell and had 61 points (12 goals, 49 assists) in 89 games. Ryan was named to the All-Ivy League First Team twice (2014, 2015) and was an All ECAC Hockey First Team selection in 2015 despite missing eight games because of an injury.

Ryan signed an entry-level contract with the Sharks on March 26, 2015, following his senior season at Cornell, and played in seven games with Worcester of the American Hockey League. Ryan spent the next two seasons with San Jose in the AHL, scoring 28 points (two goals, 26 assists) in 66 games in 2015-16, and 49 points (10 goals, 39 assists) in 65 games in 2016-17. The Sharks re-signed him to a two-year contract on June 17, 2017. Ryan made his NHL debut in a 3-2 win against the Buffalo Sabres on Oct. 12, 2017 and scored his first two career goals in a 6-4 win against the Edmonton Oilers on Feb. 10, 2018.