Scotland head coach Gregor Townsend will lead the British and Irish Lions attack in South Africa, with Steve Tandy and Robin McBryde also part of Warren Gatland's coaching team.
Wales' Neil Jenkins will embark on his fourth Lions tour as a coach.
For Townsend, Scotland defence coach Tandy and former Wales forwards coach McBryde, it will be their first tour as part of the Lions coaching team.
The first Test against the world champions is scheduled for 24 July.
"I am very pleased to have assembled such a high-quality coaching team," said Gatland.
"It's a really strong group and I'm excited to see what we can achieve together - I think we'll all complement each other well in South Africa."
Gatland is expected to name his playing squad in May.
The coronavirus pandemic had shed doubt over whether a tour of South Africa was viable but in March a contingency plan to play matches in Britain and Ireland was rejected by Lions organisers.
The original eight-fixture schedule with a warm-up Test against Japan at Murrayfield is currently under review.
Townsend 'an outstanding coach' - Gatland
Former Scotland fly-half Townsend, along with Jenkins, was part of the winning Lions team that toured South Africa in 1997.
The 47-year-old took over as Scotland coach in 2017 and earlier this year, with the help of Tandy, led the side to long-awaited Six Nations victories away to England and France.
"Gregor is doing an excellent job in charge of Scotland and is an outstanding coach," Gatland said.
"He also understands the challenges of touring South Africa as a player and what it takes to win there, so I am extremely happy he will be part of the set-up.
"Steve has made Scotland's defence one of the most organised in world rugby - something we saw throughout the recent Six Nations."
Townsend said: "As a coach the opportunity to work with some of the best players and coaches and to take on the world champions is something very exciting.
"It's going to be one of the most difficult Lions squads to pick because there's so many good players throughout the four countries."
Jenkins - who toured as a player in 2001 as well as 1997 - said it would be "incredibly special" to coach alongside former team-mate Townsend.
McBryde - who won three Grand Slams as part of Gatland's Wales coaching team - is currently an assistant coach at Irish side Leinster and has helped them to this year's European Champions Cup semi-finals as well as a fourth successive Pro14 title in March.
He will remain with the club until the conclusion of their season before joining Gatland, who added that "extra resource" could be brought in "as the tour approaches".
Who else was considered?
Gatland said there was a "challenge" over availability of other coaches who were considered to come on the tour.
Andy Farrell - defence coach on the last two tours - has decided to focus on his main role of leading Ireland, while Munster's Graham Rowntree declined so he could spend time with his family.
Leicester Tigers head coach Steve Borthwick decided to focus on club duties this summer.
"It is probably easier for international coaches to be involved because of the time-frames and probably a bit more challenging for club coaches," Gatland said.
"Yes there have been challenges [over availability], but you just have to move on. There are a couple of new faces but familiarity as well."
British and Irish Lions 2021 schedule
26 June - Japan (Murrayfield, Edinburgh)
3 July - DHL Stormers (Cape Town Stadium, Cape Town)
7 July - South Africa Invitational (Nelson Mandela Bay Stadium, Port Elizabeth)
10 July - Cell C Sharks (Jonsson Kings Park, Durban)
14 July - South Africa 'A' Team (Mbombela Stadium, Nelspruit)
17 July - Vodacom Bulls (Loftus Versfeld, Pretoria)
24 July - First Test v Springboks (Soccer City, Johannesburg)
31 July - Second Test v Springboks (Cape Town Stadium, Cape Town)
7 August - Third Test v Springboks (Ellis Park, Johannesburg)
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