Gatting started his career at Arsenal, joining as an apprentice in July 1975. He turned professional in 1977, and quickly rose up the ranks, making his first-team debut as a substitute against Lokomotiv Leipzig in a UEFA Cup match on 13 September 1978; Arsenal won 3–0. He immediately held down a first-team place, making 30 appearances in the 1978-79 season. He was not part of the squad that won the 1979 FA Cup Final, where they beat Manchester United 3–2 with a late Alan Sunderland goal. However he did contribute six appearances en route to the final; five of which came in the third round against Sheffield Wednesday (it took four replays to decide the tie, Gatting scoring one of the goals in the decisive replay) and the sixth was the semi-final against Wolverhampton Wanderers. After his playing career, he was for a time coach of the under-23s at Arsenal, but he was suspended in May 2018, alongside assistant Carl Laraman, in relation to accusations of bullying, and later released.