"During my injury rehab process, before I signed with the Nets, I was prescribed a treatment that included small doses of a substance recently added to the NBA's prohibited substance list," Chandler said in a statement provided to ESPN. "I did not realize this substance was banned, and neither did the doctor.
"I accept responsibility and apologize to my Nets teammates, coaches, front office, and fans for this mistake. I will continue to work hard to prepare for the upcoming season."
Chandler signed a one-year contract with Brooklyn in July and was set to carve out a significant role while Kevin Durant recovers from an Achilles tear.
The 6-foot-9 forward has started for the majority of his career, largely as a reliable 3-and-D option.
Chandler, 32, split time between the Philadelphia 76ers and Los Angeles Clippers last season, averaging six points and 4.2 rebounds in 51 combined games.