During 1932 close season Irish Internationalist Paddy Moore arrived at Pittodrie and it seemed that Matt Armstrong was destined for a long apprenticeship in reserve football. Indeed it has even been suggested that manager Paddy Travers had grave doubts about the ability of Armstrong to make the grade in the first team although trainer Donald Colman remained totally convinced of his abilities.

At the beginning of the 1934-35 season Moore took an unauthorised "extended leave" from Pittodrie and Matt came in to claim the first team spot for good. Almost immediately Armstrong struck up a close understanding with young inside-left Willie Mills and the Dons benefited to the tune of 39 League and Scottish Cup goals in 43 appearances.

Matt was a thrilling player to watch in action, with his greyhound-like pace and his ability to "swerve" while in full flight, and he was the perfect foil for the cultured Mills alongside him. Matt continued his superb strike rate throughout the following season and the honours started with first, Scottish League caps and finally, in October 1935 Matt was called in to the full Scottish side to face Wales. Further caps followed against Ireland five weeks later and Germany in 1936. Scotland never lost with Matt leading the line but unfortunately he never got his name on the score sheet and the selectors turned to alternative centre forwards.

The outbreak of Second World War effectively ended Matt's career at Pittodrie although he continued to assist the club during the early war years. He went on to turn out for Queen of the South and ended his career as player coach of Elgin City in the Highland League. His 136 League goals for the Dons remain a club record to this day.