Lakers athletic trainer Gary Vitti confirmed via Twitter a magnetic resonance imaging exam revealed Bryant's Achilles is ruptured and "has to be sewn back together."
Bryant limped off the floor at Staples Center late in Friday's 1198-116 win over the Golden State Warriors after gamely trying to shake off the injury.
The injury could derail the Lakers' desperate campaign to make the playoffs.
The victory Friday pulled LA one game ahead of Utah in the race for the final playoff berth in the Western Conference. The Lakers wrap up the regular season at home against San Antonio Sunday and Houston Wednesday.
Bryant, 34, ends the season with averages of 27.3 points, 6.0 assists and 5.6 rebounds in 78 games.
The guard has been in the NBA 16 years. His contract with the Lakers expires after next season and there has been speculation he will retire after that.