The Fighting Irish also announced Saturday that sophomore quarterback Tyler Buchner will start the opener against Ohio State on Sept. 3.
Davis' injury happened during practice Friday. The senior and team captain, who was penciled in to start at slot receiver, had previously injured the ACL in his left knee last November, forcing him to miss the final month of the season.
Davis still finished third on the team in yards receiving with 386 on 27 catches.
Losing Davis depletes the Irish wide receiver group further, especially in terms of experienced players. Without Davis, only two returning wide receivers have caught more than 20 passes in a season: Braden Lenzy and Lorenzo Styles. Lenzy is the only one with starting experience.
Nobody on the depth chart behind Davis has extensive game experience.
Buchner played in 10 games last season, mostly as a backup, and threw for 298 yards, 3 touchdowns and 3 interceptions last season. He also ran for 336 yards and three scores.
Buchner, a 6-foot-1, 215-pound sophomore from San Diego, had been the favorite to land the starting job. He competed with third-year sophomore Drew Pyne throughout spring practice and the early part of preseason camp.
ESPN rated Buchner as the No. 8 pocket passer and No. 41 overall player in the 2021 recruiting class.
"It was time," coach Marcus Freeman told reporters Saturday. "It was time to give the offense clarity on who was the starting quarterback."
Offensive coordinator Tommy Rees said Pyne, an ESPN 300 recruit in 2020, also could be called upon when needed. Rees told ESPN this spring that Buchner, while more reserved than Pyne, has grown into a stronger leadership role.
"Tyler's a little bit more of that quiet killer, a little bit unassuming, but when a competitive situation turns on, there's a different gear," Rees told ESPN. "Part of his growth is to be the guy who can lead, but his style is a little bit different. Tyler's confidence is through the roof, [but] you don't get that unless you really spend some time with him."
Rees said decision-making ultimately would shape the decision on the starter, but also noted that Buchner brings different elements to the offense with his mobility.
"It's something I've really focused on, putting the ball in the right spot and taking care of the football," Buchner told ESPN this spring, "but also, when things break down, having the ability to try and go make a play and make something out of nothing, is something that really separates me."
Information from ESPN's Adam Rittenberg and The Associated Press was used in this report.