Gallagher regularly topped the nation’s scoring charts in the 1960s. He debut for Cavan in 1955 at the age of 17 years, against
Sligo in the
National Football League. He won
Ulster Senior Football Championship medals in 1962, 1964, 1967 and 1969. He also won an
Ulster Junior Football Championship medal in 1962. He was captain of Cavan in 1967 and 1969. He won Railway Cup medals with
Ulster in 1964, 1965, 1966 and 1968. He won a
Cú Chulainn Award in 1964. His older brother Brian won an All-Ireland medal in 1952. ==Honours==