Luka Doncic continues to break records on and off the court ... his 2018 National Treasures Rookie NBA Logoman Patch card, a 1-of-1, just sold for $3.12 million at auction!

The ultra-rare card sold at a PWCC auction Thursday night ... and set a new all-time record for a basketball card sold at a public auction.

The card features an image of the 23-year-old hoops star on the front, along with an actual patch from a jersey he wore during his rookie year and an autograph. The back has a quote from Luka's rookie season ... when he joked he'd retire if he dunked on LeBron James.