The show, which premieres Thursday, follows vocalists as they compete to become a member of a new boy band.
"Get ready! @BoyBandABC premieres TONIGHT on @ABCNetwork. Let's go @Timbaland @nickcarter & @RitaOra! #BoyBand @BoyBandABC," Bunton tweeted to her 1.2 million followers.
Bunton and Carter became friends during the Spice Girls and Backstreet Boys' fame in the 1990s.
Carter downplayed the possibility of a joint tour between the groups in July, telling FanFest the Spice Girls were "focused on their own reunion tour." Bunton told EW her group has yet to confirm plans for a reunion.
FOLLOW REALITY TV WORLD ON THE ALL-NEW GOOGLE NEWS!
Reality TV World is now available on the all-new Google News app and website. Click here to visit our Google News page, and then click FOLLOW to add us as a news source!
"We all adore each other and are constantly in contact, but we've all got children and other projects, so it's just about getting that time together," she said. "We really appreciate that the fans have been nothing but supportive."
Copyright 2017 United Press International, Inc. (UPI). Any reproduction, republication, redistribution and/or modification of any UPI content is expressly prohibited without UPI's prior written consent.