Cassie is getting back to regular life after settling her human trafficking lawsuit against Diddy ... and her first official order of biz is a fashion show in France.

The singer popped up Wednesday at Paris Fashion Week ... making an appearance at the LGN Louis Gabriel Nouchi Menswear fashion show ... and she was looking like a straight-up model who was ready to hit the runway.

In fact, it looks like she might've actually gone down the catwalk at one point -- if this photo is any indication. Cassie went with an all-black outfit, with super dark eye shadow behind her black sunglasses ... and it looks like she meant business.

It's the first time we've seen Cassie at a public event since she settled her explosive suit with Diddy for an undisclosed sum.

Cassie was spotted in public in Connecticut back in November immediately following the rape lawsuit settlement ... but as far as official events, Paris Fashion Week is the first for her as she starts a new chapter.

Meanwhile, Diddy's stepped out from the spotlight ... as he's been hit with other lawsuits accusing him of rape/sexual assault, allegations he's vehemently denied at every juncture.

As for Cassie, she's getting a move on with things and doing her best Blue Steel in French.