The former India captain also grabbed a Worcestershire wicket with his gentle medium pace to cap a fruitful outing.
Northamptonshire overcame an early jitter and got off to a flier as Ganguly (73) and Rob White (66) came up with their personal best and put together a 105-run partnership.
Ganguly brought up his half-century and the 100 partnership in style when he launched Roger Sillence into the stands.
His 51-ball knock included four towering sixes, besides seven hits to the fence before he was run out.
Graeme Hick (55) and Lou Vincent (40) led a spirited chase for Worcestershire but Monty Panesar removed both just when things threatened to go out of control and Ganguly then claimed the wicket of Ben Smith. Ganguly's bowling figures read 4-0-32-1.