Enzo Maccarinelli recovered from two early knock-downs to take Shane McPhilbin's British cruiserweight belt.
Maccarinelli won a unanimous verdict in Wolverhampton, with the judges scoring the contest 115-111, 116-111, 115-110 in his favour.
But the 31-year-old Welshman was in severe trouble in the opening rounds as McPhilbin twice floored the challenger.
He failed to capitalise, though, and former WBO champion Maccarinelli gradually took control to win.
The victory fulfilled a career ambition for Maccarinelli, who had never before won a British title.
This was the Swansea fighter's first bout at cruiserweight since stepping down a weight to light-heavyweight in an attempt to resurrect his faltering career.
But the display did nothing to end doubts that Maccarinelli's best days are behind him as he struggled to dominate his far less illustrious opponent, who had himself fought back from two early knockdowns to dethrone champion Leon Williams in January.
Maccarinelli has returned to train with Enzo Calzaghe, but the man who guided son Joe Calzaghe to greatness was not be allowed in his fighter's corner on Friday after having his training licence withdrawn by the British Boxing Board of Control.