L.A. Fireaid is bringing out some of the big artists and providing a reason for some huge groups to link back up … even Gwen Stefani and her old bandmates are getting back together once again!

Sources with direct knowledge tell TMZ … No Doubt has just joined the already star-studded lineup for L.A. Fireaid on January 30.

As you know … No Doubt dominated the pop charts throughout the 1990s and into the early 2000s — but eventually went on several hiatuses while Gwen’s career took off.

They went on a nearly decade-long break beginning in 2015 … but, linked back up at Coachella last year — lighting up the stage out in the California desert.

Worth noting … we already knew Gwen Stefani was performing at the festival — but, now her bandmates are backing her too, which makes sense given they grew up in Orange County, not far from Los Angeles.

Among the other stars performing … Lady Gaga, Billie Eilish, the Red Hot Chili Peppers, Green Day, Jelly Roll, Gracie Abrams, Dave Matthews and John Mayer, Earth, Wind & Fire, Joni Mitchell, Katy Perry, Lil Baby, Pink, Rod Stewart, Sting, Stephen Stills, Stevie Nicks, Tate McRae and more.

The full roster for L.A. Fireaid will be released in the next few days.

The L.A. Fireaid concert — the proceeds of which will go to wildfire disaster relief — will take place at Intuit Dome and the Kia Forum in Inglewood … and, fans who want to support the endeavor can go on the website now to donate.