Isaiah Jaay had the TMZ Brunch Bus baddies going wild … getting the whole group hyped as they hit a few popular spots in Los Angeles Sunday.

The R&B singer led the bus to The Henry, The Butcher, The Baker, The Cappuccino Maker, and TomTom Restaurant & Bar in West Hollywood to cap off the long holiday weekend … belting out soulful notes on the ride and throwing in some fancy dances moves to boot.

Jaay recently served as the audience host at the “Baddies Gone Wild” reunion show … and, while our bus didn’t get as out of hand as the three-episode reunion, Jaay certainly knows how to rock a crowd just right.

The group raised a glass to TMZ at The Henry … with Jaay front and center in the craziness. Mimosas and other alcoholic beverages flowed through the afternoon as the full bus took in the local sights and sounds of Los Angeles.

And, for those who aren’t so much into alcohol, riders also got a taste of holiday cheer … some hot cocoa to get ya into the holly jolly spirit!

But, we’d never let our bus get stale … and, we’re adding a TMZ Brunch Bus this weekend with three surprise new stops … so get tickets now if this looks like your kind of party!

BTW … Jaay also filled us in on his upcoming project — and it sounds like fans can enjoy a new holiday classic when he drops a track next week.