Murchie is currently defence coach with Kobelco Kobe Steelers and will take up the role with Steve Tandy's set-up after the conclusion of the Japanese Rugby League One season in June.
Tandy knows Murchie from his time involved in Scottish rugby, having being one of Gregor Townsend's assistants from 2020 until last summer.
"It's great to welcome Pete to the coaching team," said Tandy.
"He is a really talented coach with a great style and mindset. He'll be a real asset for us as a group and I can't wait for him to join us this summer to help shape the squad's development as we head into the Nations Championship."
Murchie added: "The opportunity to move into international rugby with Wales, where there are so many exciting competitions on the horizon, was something that me and my family are hugely excited about.
"Steve was a huge driver for me, I know he is a world class coach and we have worked together closely before."