The 22-year-old was unable to complete the full 90 minutes in Sunday's goalless draw with Manchester City after pulling out of the England squad with a long-standing muscular issue.
Mikel Arteta insisted that Saka's withdrawal at the weekend was fatigue-related, and the winger was seen in training on Tuesday after the Gunners boss declared that he would be "fine" to play on Wednesday.
However, the Spaniard has ultimately avoided taking a risk on Saka's fitness, omitting him from the squad entirely to face the Hatters, and Reiss Nelson has been given the nod on the right in his absence.
The 24-year-old was left out of the matchday squad at the Etihad for tactical reasons, but he has been swiftly brought back in from the cold and is one of five changes on the hosts' end tonight.
Kai Havertz keeps his place through the middle, but Leandro Trossard takes the place of Gabriel Jesus on the left-hand side, while Gabriel Martinelli is not risked from the start after his foot problem.
Injury-plagued duo start in midfield
Similarly, only one of Arteta's midfielders - Martin Odegaard - reprises his role from the draw with the champions in the shape of Martin Odegaard, as Declan Rice and Jorginho both drop to the bench.
In their places, the injury-riddled Thomas Partey and Emile Smith Rowe will make rare Premier League starts, while Oleksandr Zinchenko replaces Jakub Kiwior at left-back in Arsenal's final change.
William Saliba and Gabriel Magalhaes continue their partnership at the back after earning rave reviews for their performance at the weekend, while Ben White holds off Takehiro Tomiyasu to start at right-back.
Meanwhile, Luton boss Rob Edwards has made three changes to the team which lost 2-1 to Tottenham Hotspur on Saturday, one of which is enforced due to the injury Reece Burke sustained last time out.
Daiki Hashioka has seemingly been shoe-horned into a central role in Burke's place, while Jordan Clark and Fred Onyedinma - making his first Premier League start of the season - replace Luke Berry and Tahith Chong respectively.
The latter has still made the bench after picking up a knock at Tottenham, while Alfie Doughty is cleared to start at left-back despite also sustaining a minor injury on the Easter weekend.
Arsenal: Raya; White, Saliba, Gabriel, Zinchenko; Odegaard, Partey, Smith Rowe; Nelson, Havertz, Trossard
Subs: Ramsdale, Tomiyasu, Kiwior, Rice, Jorginho, Vieira, Jesus, Martinelli, Nketiah
Luton Town: Kaminski; Onyedinma, Kabore, Hashioka, Mengi, Doughty; Mpanzu, Barkley, Clark; Townsend, Morris
Subs: Krul, Shea, Berry, Woodrow, Chong, Johnson, Chigozie, Nelson, Piesold