Florida Atlantic lost its second game of the season at Mississippi before reeling off 20 straight wins.
During that streak, in December, a Caesars Sportsbook bettor in Illinois wagered a total of $400 to win $800,000 on the Owls to win the national championship.
The gambler placed three $100 bets at 2,500-1 odds and one $100 bet at 500-1.
Florida Atlantic, 35-3 and riding an 11-game win streak, upset Kansas State on Saturday to advance to the Final Four and is two victories from winning the national title.
The ninth-seeded Owls are 2-point underdogs to fifth-seeded San Diego State in Saturday’s national semifinal.
“They put up a huge win total in the regular season. We had some long odds on them, and they’re being rewarded for their faith,” Caesars assistant director of trading Adam Pullen said. “They’re sitting on some big tickets and are in a good position to guarantee themselves a profit.”