Even for hard-core boxing fans, it is difficult to see how Sean O’Bradaigh emerged as a fearsome light heavyweight. His somewhat posh background, with private schooling and vacations in St. Tropez and Greece, is about as far as can be from those of Mike Tyson or Jake LaMotta.

O’Bradaigh’s father is a private wealth manager from Ireland, and his mother is a Belgian film and theater producer. He grew up in a doorman building a few blocks from the Hudson River, is a strong skier (he actually prefers Aspen to the Alps), and is fluent in French after attending the Lycée Français on the Upper East Side for 15 years. He enjoys brunch with his mother and the occasional Broadway show. He will graduate from New York University in May with a degree in real estate finance. And he can knock you out flat.

“Someone like me is not supposed to be good at boxing,” O’Bradaigh (pronounced oh-BROAD-ee) said on Wednesday while reclining on a couch in his family’s stylish living room. “To become good, you need to have been punched in the face thousands of times and do a lot difficult stuff that most people with my background aren’t willing to do. I could have quit any time, but I didn’t.”

O’Bradaigh, who turns 23 in April, will make his professional debut on Sunday at Madison Square Garden, where he watched fights as a boy. It is part of an Irish-themed boxing card, headlined by Callum Walsh vs. Dean Sutherland, on the eve of St. Patrick’s Day.

O’Bradaigh will face Jefferson Christian Almeida in the same arena where he won the 2023 Golden Gloves (now the Ring Masters) as a middleweight. He won 25 of 39 bouts as an amateur, won the New York Boxing Tournament as a light heavyweight and twice reached the semifinals of the amateur national championships.