Gunn's training and performances for the reserve team and occasional first-team appearances paid dividends: he was called up for the Scotland under-21 team, and made his debut in November 1983 against East Germany. He also received Scottish League Cup and European Cup Winners Cup winner's medals while with Aberdeen, although he was an unused substitute in both finals. He made an unexpected appearance in the 1986 European Cup quarter final, against Gothenburg. "Jim and I were warming up and he lost contact lenses [so I ended up being included in the starting line up," Gunn recalls. Gunn had an excellent match: "The Glasgow Herald"'s match report stated, "Only outstanding work by Willie Miller and Bryan Gunn kept the Swedes at bay". As well as making several key saves, he was credited with playing a part in Aberdeen's second goal following a long kick upfield.