"With such an astounding group of coaches at the peak of their musical ingenuity and Carson returning as our host, we are thrilled for what season nine will bring," NBC reality chief Paul Telegdy said.
"The expertise and camaraderie of this panel will provide an immeasurable experience for the artists and must-see entertainment for all who are watching."
Levine and Shelton have served as coaches on all eight prior seasons of The Voice.
"I can't believe we're already on the ninth season. Time after time, coming back, it honestly feels like the first day of school. Itâ€™s become a second family for me and I'm always so excited to come back to it," Levine said.
Stefani was previously a coach on The Voice's seventh season, while Williams has served as a coach on the last two seasons of the reality singing competition.
"Adam, Gwen, Pharrell and I had a blast together in Season 7 and I'm excited we're back together again. They are all so talented but I'm pretty damn excited about another winning season for Team Blake," said Shelton.