The singer-songwriter left Cabo, Mexico to get back to Los Angeles Thursday -- bringing her new furry friend back from south of the border.

She's holding her new pal tight in Mexico -- covering up most of her face with it while adding a black hat and dark sunglasses to her look.

Spears landed in Los Angeles just a few short hours later ... messing around on her phone -- with the rabbit still held close to her body.

Seems like Britney had a heck of a time down in Mexico ... like we told you, she posted her most energetic dance video yet Wednesday -- smacking her booty, shoving her thumbs in her underwear and chaotically swinging around her room.

BTW ... the rabbit made an appearance during the wild dancing clip -- staring deeply into the camera, with the whole video set to tracks off her "Blackout" album, the last she released before she was put into a years-long conservatorship.

The vid she posted earlier this week was far from the only one Brit took. She also shared another clip earlier this month in a low-cut silver top ... full of spins, kicks and more.

She claimed she planned to move to Mexico ... though, as we told you, she didn't end up doing it.