Adams, in his second year in the league, won the job over incumbent starter Kendrick Perkins, an 11-year veteran.
The 29-year-old Perkins has started each of 222 games he has played with the organization. Adams started 20 games last season when Perkins was injured.
Adams, 21, averaged 3.3 points, 4.1 rebounds and 0.7 blocks per game in just under 15 minutes of playing time last season, while Perkins averaged 3.4 points, 4.9 rebounds and 0.5 blocks per contest during 19.5 minutes of court time.
Oklahoma City will be without reigning MVP Kevin Durant until at least the end of November, after he fractured a bone in his foot. Adams, a native of New Zealand, was the 12th pick in the 2013 draft. He played one season at the University of Pittsburgh.
The Thunder open the season against the Portland Trail Blazers on Wednesday.
- Brad Rowland