Wasps have announced that Lee Blackett will arrive at the club at the end of the season, taking over from Stephen Jones as their new backs coach.
Blackett completes the Wasps coaching team of director of rugby Dai Young, defence coach Brad Davis and part-time assistant coach Andy Titterrell.
Blackett, who became the youngest coach in the Championship when he took up the role of head coach at Rotherham in 2013 at the age of 30, earned widespread respect in the game for leading the Titans to fourth spot in the Championship last season – the first time the club had reached the semi-final play-off positions in the modern championship era.
Strong performances over the season culminated in a tightly contested play-off against Bristol Rugby and the Yorkshire side are again on course for a top-four finish this season.
"We always knew the time would come when Stephen [Jones] would want to return to Wales with his young family. He's done a great job for us, after moving straight from a player to backs coach when Shane Howarth left," said Wasps boss Young.
"There were two options; option one was to recruit a vastly experienced backs coach who has been there and done it, option two was to get the best up and coming coach out there.
"The vastly experienced option was a non-starter really, simply because there is no one of that level on the market at the moment, so we decided to look at the most promising young coaches coming through the game, who have the potential to succeed at the highest level and who possess the work ethic and ability to take us to the next stage.
"Lee [Blackett] is one of the brightest young coaches in Britain, who has won admiration throughout the game for how he's turned Rotherham Titans into one of the strongest teams outside of the Premiership.
"He has impressed knowledgeable onlookers by his attention to detail, enthusiasm and professionalism and his proven ability to get the best out of the players he coaches.
"Lee has a good few years coaching experience under his belt, most recently as Head Coach in the Championship and he showed tremendous leadership in taking Rotherham to a top four finish last season.
"His attacking mind-set should also suit our squad of players, particularly the attacking threats we have in the backline. Last season he masterminded a style of rugby which saw Rotherham finish the season as the second highest points scorers in the Championship, smashing Rotherham's previous record by 222 points.
"We also believe he is the type of character who will fit in very well to the environment we have established here at Wasps."
Blackett said: "I am really excited about the new challenge ahead with Wasps next season. Even watching from the outside, you can see how much the club is moving forward and it's an exciting time for Wasps. Any coach would jump at the chance to work with the calibre of players Wasps have at their disposal.
"When you watch Wasps playing at their best, at pace, you see how devastating they are. The number of tries and points Wasps have scored this season shows what a quality outfit they are and I'm very much looking forward to being a part of that next season.
"I'm also really looking forward to working with Dai Young and the Wasps' coaching team. I enjoy talking to coaches world-wide and I view this as a massive opportunity to learn from coaches who have enjoyed success at the highest level.
"I'd like to thank the Rotherham directors who gave me the opportunity as Head Coach and I hope I've repaid them. As a coach, you are very reliant on players and a massive thank you must also go to them for how hard they have worked and played. I'm very appreciative of all the support I've been given by directors, players, supporters and everyone involved at Rotherham.
"As anyone who knows me will tell you, I will be fully committed to Rotherham for the rest of the season. It's the Titans first and there won't be a spare second to think about anything other than our push for a play-off place. It's massively important for the club and it would be great to go out on a high by reaching the play-offs in successive years."