The deal's financial terms aren't yet known, but the contract is for two years, according to Wojnarowski.
Gasol, 35, spent last season and part of the 2018-19 campaign with the Toronto Raptors, where he won an NBA Championship in 2019. He suited up for the Memphis Grizzlies for 11 seasons before being dealt to the Raps, but Gasol's ties to the Lakers run deep.
Gasol appeared in 44 regular-season games for Toronto last season, averaging 7.5 points, 6.3 rebounds, and 3.3 assists. The Spaniard is a three-time All-Star, won the 2013 Defensive Player of the Year, and is a two-time All-NBA selection.
The Lakers traded JaVale McGee to the Cleveland Cavaliers earlier Sunday to make room for Gasol.
The Raptors, who also lost Serge Ibaka to free agency, acted swiftly after Gasol decided to head to Los Angeles, scooping up former Phoenix Suns center Aron Baynes on a two-year deal.