Jason Kelce's flying by on luck alone this weekend -- betting thousands at a craps table before Sunday's Super Bowl kickoff.

TMZ has obtained photos of the big Philadelphia Eagles center shooting dice at a craps table in The Cosmopolitan of Las Vegas ... with eyewitnesses telling us JK  was playing at a high roller's table in the luxurious Vegas hot spot.

We're told the minimum bet was $1,000 while the max was $5,000 ... a pretty penny for Jason, but nothing his reported career earnings of more than $81 million won't cover.

Kelce was letting it ride with his ride or die at his side -- Kylie Kelce stood alongside him, cheering him on with the little crowd that gathered around the Super Bowl champion.

Seems like he might've won a bit too ... we're hearing he was hootin' and hollerin' a bit after a couple throws -- so maybe he's made a few bucks at the table.

Of course, we all know why Jason's in L.V. -- his little bro Travis Kelce's attempting to win his third Super Bowl ring with the Kansas City Chiefs against the NFC champion San Francisco 49ers.

Jason's been a pretty public supporter of K.C. since his own Philadelphia Eagles were booted from the playoffs by the Tampa Bay Buccaneers in embarrassing fashion last month -- a 32-9 slaughter by TB.