The junior said on Twitter that he "messed up a ligament" playing basketball and "it'll come out the socket if I roll it again."
Allen will undergo surgery Thursday, Tedford said on Twitter, but should be recovered in time for voluntary summer workouts.
Allen caught 98 passes for 1,343 yards and six touchdowns last season, earning first-team All-Pac-12 honors, after amassing 46 catches for 490 yards and five scores as a true freshman. The school is already touting him as a All-America candidate this season, though he will face still competition from within the conference to do so.
One of his main challengers will be USC junior wide receiver Robert Woods, who ironically suffered a similar injury last year. Woods rolled his ankle in a pickup game one day before the end of spring practice, an injury that lingered throughout the season. His absence will offer additional opportunities in practice to several inexperienced returning players as Cal looks to replace departed seniors Marvin Jones and Michael Calvin.
Tedford said Monday during a conference call with reporters that he was looking forward to seeing what redshirt freshman Maurice Harris, the cousin of Allen and Cal quarterback Zach Maynard, and Stephen Anderson could contribute.
Cal also signed five freshmen that are expected to challenge for playing time in the fall.