Stefani, 51, who formed the rock band in 1986 with guitarist Tom Dumont, bassist Tony Kanal, and drummer Adrian Young, posted a video thanking their fans for their continued support. In the clip, she noticeably rocks two necklaces, one with her last name and another one that reads "Shelton," in honor of her boyfriend, Blake Shelton.
"I have so many memories. So many people that I've met through the years that have told me that that's their favorite record," Stefani shared. "I didn't even think it would come out, let alone have people love it and listen to it and it be their favorite. I feel like I'm still just a girl from Orange County, but I have all these blessings."
Stefani also thanked her former bandmates, adding that their fans' support "just fuels my fire and music makes the world go 'round."
The rest of the No Doubt members also celebrated their album's anniversary. Kanal posted two group photos, writing in part, "We had already been a band for 9 years before Tragic Kingdom came out. We had no idea what was going to happen when we were writing these songs."
"Through all of the fun and challenging times, we were just a group of friends on a mission to express ourselves musically. Sometimes It felt like it was us against the world but our love for our band got us through it all," he added.
Young posted the album cover, writing how they had "no idea that our lives were about to dramatically change as a result."
"Thank you to those who have shared this crazy and spectacular ride with us! Knowing that this record has touched so many of your lives makes the recognition of this day that much more special!" Young continued.
Dumont shared a photo from their time in Hawaii in 1995, reflecting on his time in the band.
"I can’t believe it’s been 25 years, in some ways it feels like yesterday, in some ways it feels like a distant dream," he began, before touching on the band going their separate ways. "Sometimes great things fall apart, which is a shame. Yet here we are, 25 years later. It is what it is, & I keep trying to make peace with that."
"I’m especially grateful to all those who helped us along the way, and most of all to those of you who enjoyed Tragic Kingdom and came out to the shows over the years," he continued. "I’d love to do one more No Doubt tour, but it feels like that ain’t gonna happen. It’s bittersweet. In any case, what great memories, thanks all."
After six studio albums -- with 2012's Push and Shove being their last -- No Doubt went on an indefinite hiatus in 2015. Stefani has continued as a solo act. In 2016, Kanal, Young and Dumont teamed up with AFI lead singer Davey Havok to form the new wave supergroup Dreamcar.