Alun Wyn Jones has been named as Captain of the British and Irish Lions, with Justin Tipuric also named in the 37-man squad.
“We believe we’ve picked a squad capable of winning a Test series in South Africa,” said Gatland.
“Selecting a Lions squad is never easy and, in many ways, this has been the most challenging selection I have been involved in. Over the course of the last three weeks the coaches and I have rigorously debated each position. We saw some outstanding performances in the recent Six Nations, so competition for places has been tough with some incredibly tight calls to make.
“However, we are very happy with the squad we have assembled and look forward to meeting up in Jersey in just over a month’s time to start our preparation to take on the World Champions. We've left out some very talented players which gives an indication to the strength of this squad and we know how important that stand-by list will be.
“Being selected for a Lions Tour is the greatest honour for a British and Irish player and I congratulate everyone named today.”
Backs (16):
Josh Adams (Cardiff Rugby, Wales) – Wing
Bundee Aki (Connacht Rugby, Ireland) – Centre
Dan Biggar (Northampton Saints, Wales) – Fly-half #821
Elliot Daly (Saracens, England) – Centre #822
Gareth Davies (Scarlets, Wales) – Scrum-half
Owen Farrell (Saracens, England) – Fly-half #780
Chris Harris (Gloucester Rugby, Scotland) – Centre
Robbie Henshaw (Leinster Rugby, Ireland) – Centre #824
Stuart Hogg (Exeter Chiefs, Scotland) – Full-back #783
Conor Murray (Munster Rugby, Ireland) – Scrum-half #790
Ali Price (Glasgow Warriors, Scotland) – Scrum-half
Louis Rees-Zammit (Gloucester Rugby, Wales) – Wing
Finn Russell (Racing 92, Scotland) – Fly-half #835
Duhan van der Merwe (Edinburgh Rugby, Scotland) – Wing
Anthony Watson (Bath Rugby, England) – Wing #816
Liam Williams (Scarlets, Wales) – Full-back #833
Forwards (21):
Tadhg Beirne (Munster Rugby, Ireland) – Second row
Jack Conan (Leinster Rugby, Ireland) – Back row
Luke Cowan-Dickie (Exeter Chiefs, England) – Hooker
Tom Curry (Sale Sharks, England) – Back row
Zander Fagerson (Glasgow Warriors, Scotland) – Prop
Taulupe Faletau (Bath Rugby, Wales) – Back row #779
Tadhg Furlong (Leinster Rugby, Ireland) – Prop #818
Jamie George (Saracens, England) – Hooker #819
Iain Henderson (Ulster Rugby, Ireland) – Second row #808
Jonny Hill (Exeter Chiefs, England) – Second row
Maro Itoje (Saracens, England) – Second row #825
Alun Wyn Jones (Ospreys, Wales) (Captain) – Second row #761
Wyn Jones (Scarlets, Wales) – Prop
Courtney Lawes (Northampton Saints, England) – Second row #826
Ken Owens (Scarlets, Wales) – Hooker #829
Andrew Porter (Leinster Rugby, Ireland) – Prop
Sam Simmonds (Exeter Chiefs, England) – Back row
Rory Sutherland (Edinburgh Rugby, Scotland) – Prop
Justin Tipuric (Ospreys, Wales) – Back row #786
Mako Vunipola (Saracens, England) – Prop #787
Hamish Watson (Edinburgh Rugby, Scotland) – Back row