Dai Young has left Wasps after nine years as director of rugby.
It was announced last week that the 52-year-old would be "stepping back" from first-team duties, but his departure from the club has now been confirmed.
Wasps, who are 10th in the table after 10 games, were Premiership runners-up in 2017 but never won a major trophy during Young's tenure.
Young said he was "proud" of his record, but that it was "the right time for both the club and myself" to leave.
"It will be tough to leave a club and group of people that has meant so much to me over the past decade," added Young. "It has been a fantastic experience for myself and my family."
Lee Blackett, 37, has been named as interim head coach having worked under Young as attack and backs coach.
Young, a former dual code Wales international and British and Irish Lion, joined Wasps in 2011 from Cardiff Blues.
Having reached the Premiership play-offs in three successive seasons between 2016 and 2018, they have only won 13 of their past 47 matches in all competitions and have been knocked out of Europe early in each of the past two years.
The Coventry-based outfit have also lost many of their big names during that period, including England's Elliot Daly to Saracens last summer, as well as World Cup winner Willie Le Roux, Kurtley Beale, Danny Cipriani and Christian Wade.
They are just two points above 11th-placed Leicester after losing to Tigers on Saturday, but with Saracens' relegation already confirmed following their salary cap breaches in previous seasons, Wasps are spared any concerns of dropping down to the Championship.
"I'd like to place my sincere thanks on record to Dai for his hard work and support over the years," said chairman Derek Richardson.
"He has done a tremendous job and, in particular, I'd like to thank him for his advice and help when I first became involved with the club, and also his support for the move to Coventry in 2014."