Webb made the decision Wednesday after meeting with team doctors and three other physicians.
The 2006 NL Cy Young Award winner, who won 56 games from 2006-08, has been sidelined since opening day. He will begin a regimen to strengthen the shoulder but isn't expected to throw for several weeks. There is no timetable for his return.
"After meeting with several doctors, 'Webby' has decided to proceed with a conservative course of treatment," Arizona general manager Josh Byrnes said in an e-mail message. "We are optimistic that this will give him the best chance to return to pitching."
Webb was in Birmingham, Ala., on Wednesday while the Diamondbacks were in Cincinnati for the second game of their series against the Reds. Webb will spend a few more days on Birmingham working with a therapist before rejoining the team, manager A.J. Hinch said.
Webb, who won 22 games last season, made only one start before going on the disabled list with a sore shoulder. He had a setback last month while playing catch, prompting him to see several doctors to get advice on whether to have surgery or try to let the shoulder heal with rest and a strengthening program.
Three doctors recommended the conservative approach, which Webb embraced.
"He's thrilled with the prognosis and the plan that's been set for him," said Hinch, who talked to Webb by phone earlier Wednesday. "His whole idea is to get better, to just get to throwing free and easy again and get back on a major league mound.
"He wants to pitch this year. He's not mortgaging the year. So that was the exciting part to come out of it. He's got his mind prepared to get back to competing this year as soon as his health dictates it's possible."
Webb won't throw for the next two to four weeks, focusing instead on increasing his range of motion and getting the inflammation out of his shoulder.
His decision to forgo surgery was first reported by MLB.com.