Gavin Mullin (born 29 November 1997) is an Irish rugby union player.

Like his father, Mullin attended Blackrock College, winning a Leinster Schools Junior Cup medal in 2013.

Mullin was part of the team that lost against hosts the Georgia U-20s, for the first ever time, resulting in a then joint-worst ever finish of ninth at the World Rugby Under 20 Championship.

He was a member of the team at the 2020 Summer Olympics in Tokyo, held in 2021 due to the COVID-19 pandemic.

He also competed for Ireland in rugby sevens events at the 2024 Summer Olympics in Paris.