St Johnstone earned their sixth win in their opening seven Scottish Championship games to move eight points clear at the summit.
Jamie Gullan and Cheick Diabate had last season's relegated side two up inside 19 minutes.
And although Airdrie pulled one back through Cameron Cooper in the second half, it was not enough to prevent Simo Valakari's visitors from extending their splendid start to the season.
Nearest rivals Raith Rovers and Arbroath are eight point adrift, having played the same number of matches.
