The win will be a relief to Saints coach Wayne Smith after a draw with Sale and a loss to Bath in their previous two games, although for Wasps it marked their second defeat in three outings.
An early try from Irish flanker Jonny O'Connor opened the try-scoring for Wasps after a break from centre Ayoola Erinle, with Van Gisbergen converting and adding a penalty.
Two penalties from Northampton fly-half Shane Drahm kept the hosts in it, and it was a crossfield bomb from the Aussie which led to Northampton's first try, Kiwi wing Bruce Reihana plucking it out of the air to claim the touch-down – Drahm converting.
Former Bristol man Drahm added a third penalty before the break to see his side in with a 16-10 interval lead.
The second half was a tight affair, with two Drahm penalties being Northampton's main contribution to the scoring, as well as a late try for debutant academy wing John Clarke.
Wasps scrum-half Peter Richards – starting ahead of veteran Rob Howley – had scored a try for the visitors nine minutes into the half, converted by Van Gisbergen, but it was to be in vain as they did not claim even a bonus point.
For Northampton Saints:Tries: Reihana, ClarkeCon: DrahmPens: Drahm 5
For London Wasps:Tries: O'Connor, RichardsCons: Van Gisbergen 2Pen: Van Gisbergen