The team made the announcement on Tuesday. Terms of the deal were not disclosed.
The 34-year-old Collison is the longest tenured member of the organization. The 6-foot-10 Collison ranks among the franchise's all-time career leaders in rebounds (3rd, 4,370 career rebounds), blocks (6th, 439 career blocks), field goal percentage (2nd, .537) and games played (2nd, 791 career games). He is averaging 3.8 points, 3.4 rebounds and 1.2 assists in 15.9 minutes per game this season, and holds career averages of 6.4 points and 5.5 rebounds.
The Seattle SuperSonics drafted Collison 12th overall in 2003, several years before the franchise moved to Oklahoma City.