The second-placed champions moved onto 42 points from 18 games, a point behind PSV Eindhoven who visit Vitesse Arnhem on Saturday, after dominating the game at the Amsterdam ArenA.
Kishna netted with the outside of his boot for Frank de Boer's side after 15 minutes having been expertly released by Lasse Schoene.
With only one goal to show for their initial endeavours, Ajax could have been at risk on the counter-attack but Groningen never seriously troubled goalkeeper Jasper Cillessen despite the best efforts of forward Jarchinio Antonia.
Ajax defender Mike van der Hoorn, who had an excellent game, nearly doubled their advantage but headed wide from a corner before a Johan Kappelhof own goal late on made it 2-0.
Groningen stay eighth with 24 points from 18 games.
Ajax welcome fierce rivals and third-placed Feyenoord a week on Sunday in the Dutch Klassieker.
(Writing by Mark Meadows; Editing by Ken Ferris)
Share
