Former Wales wing Jones will join Howley, Robin McBryde, Shaun Edwards and Neil Jenkins in plotting Wales' Six Nations title defence, which begins against Ireland at the Millennium Stadium on February 2. Jones, the current Scarlets attack coach, will have specific responsibility for the Wales backs throughout the Six Nations campaign.
"Mark is an important addition to the coaching team," said Howley, in charge while Warren Gatland makes full-time preparations for heading up this summer's British and Irish Lions tour to Australia.
"He has played the game at the highest level and developed his coaching skills during his time with the Scarlets. He is a 'hands-on coach' and understands how our environment works, which is important leading into the tournament.
"I would like to thank Simon Easterby (Scarlets head coach) for allowing Mark to join us and to start work immediately. We have always been an integrated coaching team, and Mark will be a great addition alongside Robin, Shaun and Neil."
Jones, 33, had already been confirmed as part of the Wales coaching team for a two-Test tour to Japan in June, but he is now on board for the Six Nations as well.
"I am looking forward to this exciting opportunity for me to develop further as a coach," Jones said. "It will help me to explore new ideas and gain wider experience that I hope will, in turn, benefit my full-time role with the Scarlets region."
Scarlets chief executive Mark Davies described the Wales opportunity as an "exciting" one for Builth Wells-born Jones, whose playing career was ended by injury in August 2010. Davies said: "As a region, our belief is to develop and support the talent we have invested in at the Scarlets, and to see people reach their full potential.
"That philosophy applies as much to our coaching set-up as it does to our players. This will be an important landmark and a valuable experience for Mark as he progresses as a top-class coach.
"I am sure he will give all he has to Wales in the forthcoming campaign with his trademark energy and determination. He has our full support in this exciting opportunity."
- Sports & Recreation