The L.A. FireAid concert might be the most star-studded show in history ... 'cause they just added three more big names -- Olivia Rodrigo, Stevie Wonder and Peso Pluma!

Sources with direct knowledge tell TMZ ... the three superstar singers are set to join the other 20 or so performers at the January 30 show, split between Intuit Dome and the Kia Forum.

The three stars hit a lot of different generational gaps and music genres -- a little something for everyone at the fundraiser meant to support rebuilding efforts after the devastating wildfires in the City of Angels.

Rodrigo is SoCal born and raised ... while Stevie and Peso have made it their adopted homes since moving from Michigan and Mexico respectively.

They join a laundry list of names including 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.

We also told you No Doubt -- making a rare pop reunion -- are also set to perform at the show. Fans who want to donate to the cause can do to the concert's website now.

So, no reason to feel "Sour" or "Superstitious" pop fans ... just go get your tickets when they go live next week and enjoy the show!