The club's director of rugby, who has led Wasps to consecutive Zurich Premiership titles, the Heineken Cup and Parker Pen Challenge Cup in two seasons, has asked to be released from the final year of his contract.
The club's chairman, Chris Wright, said he was "surprised and saddened" by Gatland's request, adding that the board would discuss the matter on 22 February. However, they are unlikely to stand in his way.
"I've had a fantastic time, but there comes a time when one has to choose between job and family - and for once I've decided to put my family first," Gatland, a former Ireland coach, said: "We still have plenty of work to do this season as we hope to secure a third Premiership title."
Wasps will now have to decide whether to appoint a replacement from within - the former Great Britain rugby league international Shaun Edwards is the likely candidate - or go for a more experienced candidate.
Whoever gets the job will have extremely large shoes to fill - the Gatland years will be remembered as the most successful period in Wasps' 138-year history.