Rowntree steps up into the forwards coaching role that Gatland assumed in 2009, while Howley continues as backs coach. Joining them will be former England dual-code international Andy Farrell. He will act as defence coach.
"I am delighted with today's appointments and confident that Rob, Graham, Andy and myself can come together quickly to face one of the hardest rugby challenges. Lions tours are unique as we have to mold together players from four different countries in an incredibly short space of time," said Gatland.
"We have no illusion as to the hard work required but we have spoken of the challenges and truly believe that as a coaching team we can provide the players with the support and environment needed for victory in Australia. We will also discuss over the coming weeks the requirement for any further technical assistance.
"Using the experience from 2009, which we felt we all learned a heck of a lot from, we wanted to keep some continuity with coaches and add a bit of freshness as well. We were disappointed not to come away with a series win in South Africa.
"Graham and I have kept closely in touch since 2009 and I felt more than comfortable working with him again. This is part of his progression as a coach, stepping up with England and now as forwards coach with the Lions.
"To be honest, picking Andy is a bit of a selfish appointment. It gives me the chance to work with someone with fresh ideas who I haven't worked with before. It will enable me to develop and look at the game differently as well."
The appointment of three assistant coaches represents a major milestone on the road to the 2013 tour, which kicks-off in Hong Kong on June 1 with a game against the Barbarians.
"This is the next chapter in the 2013 tour story," said tour manager Andy Irvine.
"The selection of the coaching staff is significant and this experienced trio have proven track records and we are delighted to have them on board.
"In the areas of coaching, logistics, media, performance analysis and medical, there is real continuity from previous tours, especially 2009. This is important as they all understand the challenges that lie ahead and the experience gained in South Africa will be essential as we head to Australia next year."
Irvine also announced that Dr James Robson will once again lead the tour medical team. Robson is the national team doctor for the Scottish Rugby Union, a role he has occupied since 2002. This will be his sixth successive Lions tour following his initial appointment on the 1993 tour to New Zealand.
"The entire management team is delighted that James is onboard once again," added Irvine.
"His extensive experience of all things 'Lions' is invaluable, and his knowledge of player management in terms of welfare and medical assistance is second to none. I congratulate James on this amazing personal milestone of six tours and know that once again he will give everything to ensure the players are ready for the onfield challenges."
2013 British & Irish Lions tour management team
(appointments to date)
CEO: John Feehan
Tour Manager: Andy Irvine
Director of Tour Operations: Guy Richardson
Logistics Officer: Gerard Carmody
Baggage Master: Patrick O'Reilly (Rala)
Lawyer: Max Duthie
Head of Security: Neil Strang
Coaching and Conditioning
Head Coach: Warren Gatland
Assistant Coach: Rob Howley
Assistant Coach: Graham Rowntree
Assistant Coach: Andy Farrell
Head of Strength & Conditioning: Adam Beard
Fitness Coach: Paul Stridgeon
Head of Performance Analysis: Rhys Long
Performance Analyst: Rhodri Bown
Head of Medical: Dr James Robson
Physiotherapist: Prav Mathema
Physiotherapist: Phil Pask
Media and Communications
Head of Media & Communications: Greg Thomas
Media Manager: Dave Barton
Communications Manager: Christine Connolly