The announcement came at the NBA Board of Governors meeting in New York. The league also said Deputy Commissioner Adam Silver would replace Stern.
Stern, 70, succeeded Larry O'Brien as the NBA's fourth commissioner on Feb. 1, 1984, meaning he will have guided the NBA for 30 years.
"I don't know what else to say other than to recite what I told the owners yesterday in executive session," Stern said. "I told them that it's been a great run, it will continue for another 15 months, that the league is in, I think, terrific condition."
The NBA battled through four labor lockouts during Stern's tenure, the most recent was last year, which saw the regular-season season delayed nearly two months but ended with a collective bargaining agreement covering 10 years.
Stern became the NBA general counsel in 1978 and helped the league negotiate a salary cap and a drug-testing program with the NBA Players' Association. The league has added seven teams since Stern became commissioner and established an international footprint, considered a vital move for marketing the NBA. The WNBA started play under Stern's leadership.
"I said that I like to think that I did an adequate job but one of the things that I did best was to provide a successor that would be able to take kinds of things that we now look at as huge growth opportunities -- international, digital, television negotiations -- and have somebody in place," Stern said.
Silver, 50, has been with the NBA for 16 years. He has been the league's deputy commissioner and chief operating officer since July 2006.
Also at the Board of Governors meeting, the league approved the sale of the Memphis Grizzlies to a group led by Robert Pera and elected San Antonio Spurs Chief Executive Officer Peter Holt as chairman.