Sean Holley will join the Scarlets coaching staff during this season's Six Nations.
The former Ospreys head coach will work alongside Simon Easterby and his coaching team, the Scarlets announced.
Holley (42) will work as backs and skills coach while Jones is away from Scarlets duty.
Easterby said: "To have a coach of Sean's experience, expertise and technical ability at a key time for us is vital as Mark goes away on Wales duty.
"Mark has contributed a great deal to our rugby environment and team this season and deserves his opportunity with Wales, and we are pleased to support the national set-up and his coaching development.
"We have a crucial period ahead of us while nine of our senior players are away during the Six Nations, and we need to make significant progress in the Pro12.
"We are fortunate, given the time frame and being midway through the season, to have secured the services of someone of Sean's capability and background."