A left back, Callaghan joined First Division club Fulham as an apprentice in 1962 and made his first senior appearances during the 1963–64 season.
[4][2] By the 1966–67 season, he had broken into the starting lineup on a regular basis, but was part of the team which suffered a double relegation from the First to the Third Division in 1968 and 1969.
[4] Callaghan had a long managerial and coaching career in non-League football and held roles at Enfield, Woking, Basingstoke Town, Wealdstone, Carshalton Athletic, Walton & Hersham and Kingstonian.
[12] After Dodgin Jr. was given a "leave of absence" in March 1980, Callaghan returned to Griffin Park as caretaker manager until the end of the 1979–80 season.
[2] After some positive early results, he signed a two-year permanent contract in April 1980 and managed the Bees to an 18th-place finish, clear of the Third Division relegation places.