Brody Jenner DJs and Hangs with Girlfriend Josie Canseco

Brody Jenner is back in circulation ... as if the whole "marriage" thing never happened.

Brody was at the 1720 venue in DTLA Friday night, and was super effective in hyping up the crowd. At one point he took the stage with his band, AHZ, and tried his hand at the synthesizer ... at least that's what it looks like.

Brody's new girl, Josie Canseco, was front and center ... hanging with Brody after the show. They left together at around 1:30 AM.

Seems clear ... Kaitlynn Carter's in his rear view, as she's in Miley's full view. So, now Brody's separated from Kaitlynn, Miley's separated from Liam, Brody's moved on and Liam's hanging in Australia with his brother, Chris.

Brody and Josie have been inseparable this week ... hitting up Warwick, house parties, etc.

They met during a 'Hills' press tour in NYC. Frankie Delgado and Brandon Lee made the intro.