Flanker Peter O'Mahony captains the side in Rotorua, with tour skipper Sam Warburton on the replacements' bench.
Maro Itoje starts at lock in an otherwise unchanged pack from the one that beat the Crusaders last Saturday.
"Even though it's a strong side we have to make sure we aren't fully showing our hand," said boss Warren Gatland.
"We need to keep the All Blacks guessing a little bit about what the final squad [for the first Test] may be."
Sexton, 31, has not started since the first match of the tour against the Provincial Barbarians, but came off the bench to good effect in the win over the Crusaders in Christchurch.
He partners fellow Irishman Conor Murray at half-back.
"Johnny needs some more rugby and he's got a bit of his mojo back, so we wanted to give him a start," Gatland added.
Farrell is among the replacements, and Gatland says there is "every chance" he will play alongside Sexton at some point in the game.
Gatland has previously played down the possibility of Farrell and Sexton operating in the same backline.
"Owen Farrell has had quite a bit of rugby and he's pretty important to us at the moment," Gatland said.
"We need to make sure he is fit for the following week, because he has been pretty crucial to us.
"He is on the bench and he can come on and we could end up with a 10/12 combination [with Sexton], or we can end up with him coming on at 10.
"At some point he will get some game time."
Maori All Blacks: J Lowe; N Milner-Skudder, M Proctor, C Ngatai, R Ioane; D McKenzie, T Kerr-Barlow; K Hames, A Dixon (capt), B May, J Wheeler, T Franklin, A Ioane, E Dixon, L Messam.
Replacements: H Elliot, C Eves, M Renata, L Price, K Pryor, B Hall, I West, R Thompson.
Lions: L Halfpenny (Wales); A Watson (England), J Davies (Wales), B Te'o (England), G North (Wales); J Sexton, C Murray (both Ireland); M Vunipola, J George (both England), T Furlong (Ireland), M Itoje, G Kruis (both England), P O'Mahony (capt, Ireland), S O'Brien (Ireland), T Faletau (Wales).
Replacements: K Owens (Wales), J McGrath (Ireland), K Sinckler (England), I Henderson (Ireland), S Warburton (Wales), G Laidlaw (Scotland), O Farrell, E Daly (both England).
Gatland says Warburton is aware of the competition he faces in the back row if he is to start the first Test against the All Blacks on 24 June.
Warburton returned from a minor ankle injury to play over an hour in the midweek defeat by the Highlanders in Dunedin.
"He is fully aware that loose-forward trio went extremely well against the Crusaders," Gatland said.
"This tour isn't about Sam Warburton, it's about putting the squad first, so if he isn't involved in the first Test he will fully understand that."
Elswehere, Ben Te'o is alongside Jonathan Davies in the midfield, with George North, Anthony Watson and Leigh Halfpenny in the back three.
Liam Williams does not feature in the matchday squad for the second successive game.
Mako Vunipola, Jamie George and Tadgh Furlong continue their combination in the front row.
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Gatland says a fixture against the Maori is one of the "unique spectacles in world rugby".
The Maori starting XV features experienced All Blacks such as scrum-half Tawera Kerr-Barlow and wing Nehe Milner-Skudder.
The potent backline also includes fly-half Damian McKenzie, Charlie Ngatai and Reiko Ioane, who scored against the Lions for the Blues and has been named in the New Zealand squad for the Test matches.
"We experienced a powerful powhiri on Monday which really resonated with the boys and it's been great to be here in Rotorua and feel all the support," said Maori head coach Colin Cooper.
"It's really lifted the team and helped bring them together as a unit. We recognise the challenge that is ahead of us on Saturday, but we're really excited as a group by the opportunity we have to represent New Zealand, Maoridom and the fans that will descend on Rotorua this weekend."
Johnny Sexton has been preferred to Owen Farrell at fly-half for Saturday's British and Irish Lions match with the Maori All Blacks.