Away from rugby, Mooar was admitted as a barrister and solicitor to High Court of New Zealand in 1997.
Daniels spoke glowingly of Mooar's appointment.
"After a detailed and comprehensive search we are delighted to have secured an exceptional coach in Brad," Daniels said. "As part of the recruitment process we have taken extensive references on all candidates and what came through loud and clear on Brad was that he is one of New Zealand's best coaching prospects and destined for great things.
"We pride ourselves in appointing players and coaches that not only perform on the rugby field but also contribute to the ethos and environment of the club and our wider community. Brad's rugby philosophy, leadership style and personality are everything we were looking for in a head coach.
"Throughout the process we have been hugely impressed with Brad's appreciation of Scarlets' place in the community, his passion for developing players and the research he had done on our heritage.
"We are very much looking forward to welcoming Brad and his family to West Wales, we're excited for the future but we still have everything to play for this season which will remain our primary focus."
Mooar added: "It's never an easy decision to step away from an environment that means so much to you and, come the end of the Super Rugby season, the moment will no doubt be bittersweet.
"However the opportunity to take on the role of head coach at the Scarlets is simply too good to pass up and is both an exciting challenge for myself, and a fantastic opportunity for my family to experience life on the other side of the world.
"Scarlets is a winning club with an extremely proud history, passionate fans, and is aspirational in its goals. It is humbling to be offered the opportunity to take the reins after the great work Wayne Pivac has led, as he moves on to the Wales job.
"I'm incredibly proud of what we have achieved during my time at the Crusaders, and I'm certainly focused and looking forward to one final campaign alongside this special group of coaches, management and players."