Green’s Dictionary of Slang

(Scot./Ulster) well-dressed.

1935		(con. 1920s) McArthur & Long No Mean City 6: Arthur Ross was ‘well put on.’ He wore a neat blue suit and a bowler hat.
1936		K. Mackenzie Living Rough 161: I figured in Glaswegian language that I was ‘well put on’ in my new paraffin.
1997		Share Slanguage.