After appearing in several Mack Sennett-directed silent films of the 1920s, Finlayson made a name for himself as a comedic actor in over two dozen Laurel and Hardy movies of the 1920s and 1930s.
He appeared in the 1916 Broadway tour of Bunty Pulls the Strings, but left the show to pursue a Hollywood acting career.
He became famous for his trademark comedic double take mannerism, as well as for his frequent and humorous use of the expression "d'ooooooh."
He and his brother Robert grew up in Larbert, Stirlingshire, Scotland as the children of Alexander Finlayson and Isabella Henderson. At the age of thirty-two, he married Emily Cora Gilbert.
His many films with the Stan Laurel and Oliver Hardy comedy team include Near Dublin, No Man's Law, and Yes, Yes, Nanette.