Gemmill joined Nottingham Forest for £25,000 in September 1977 becoming the third ex Derby title winning player of Clough's to join him at Forest. John O'Hare and John McGovern were the other two. He played 58 times for Forest in the league, scoring three goals. He was integral to the success of the club in the late 1970s, but was dropped for the 1979 European Cup Final. Gemmill referred to the decision later: