The ex-Migos rapper made it to the debut screening of the highly-anticipated flick -- which stars Halle Bailey as Ariel -- in Los Angeles ... where he and his daughter -- 8-year-old Kalea and 4-year-old Kulture -- walked the blue carpet as they were headed into the theater.

Their outfits were on point/on theme ... Offset was dressed to the nines, wearing an ensemble that strongly resembled what Prince Eric wears in the animated flick -- complete with a white jacket, black pants and shiny matching boots. His kids were even cuter.

Kalea and Kulture each donned gorgeous mini gowns and tiaras, looking like they were being taken to the ball that Cinderella went to in the fairy tale. Kalea even had her hair dyed red, just like Ariel does in the cartoon and just like Halle in the live-action film. It's clear the family was excited to see this one on the big screen -- and probably for good reason too.

As you may know ... Halle being cast as Ariel -- who's portrayed as white in the OG -- was a big deal in the African-American community ... serving as a crucial point of representation that hadn't really been seen before. Little Black girls everywhere reacted to the trailer when it came out ... and they all pretty much seemed to be in awe that Ariel looked like them.

Of course, there's been some backlash as well ... some of which, you could argue, is steeped in racism. No matter though -- the film's still coming out ... and it's a big deal.

No sign of Cardi here, which is fine. Looks like this was a dad-daughter date that Offset was more than happy to handle on his own -- and he certainly stepped up to the plate.