Gunn commenced his professional career with Aberdeen in 1980, (signing a week prior to Eric Black who came from the same part of the country) and forged a good relationship with then-Aberdeen manager Alex Ferguson—evidenced by the fact that in 1997 Ferguson brought Manchester United to Carrow Road for Gunn's testimonial match. While an apprentice at Aberdeen, Gunn was a frequent babysitter for Ferguson's children. He later said, "I probably babysat more than I played". Gunn portrays the relationship as warm, but businesslike: