Curtis Woodhouse confirmed he will retire despite winning the British light-welterweight title on a split decision from Darren Hamilton.
Woodhouse, the former professional footballer who switched to the ring eight years ago, had promised this would be his last fight - win, lose or draw.
After 12 rounds of non-stop action at Hull's Ice Arena, two of the judges gave Woodhouse the verdict by margins of 116-115 and 116-114, while the other scored it 116-113 for defending champion Hamilton.
Woodhouse, who improved his overall record to 22-6, said: "When I was 10 years old, they told me I can't be a footballer, everyone laughed at me.
"When I said I was going to be a professional boxer, everyone laughed at me again. I had the audacity to say I was going to be a British champion, I honestly can't believe this has happened."
On his retirement plan, he added: "How can I ever top what has happened tonight, this will never get better for me. I wanted to bow out as champion and aim to stick to that.
"There's a rumor going around - that I can neither confirm or deny - I had a £5,000 bet on myself to win the British title at 50/1. The drinks are on me baby!"
Bristol-based Hamilton was making the third defense of his British belt and had gone the distance in each of his last four contests.
It again followed a similar script with nearly every round closely fought, leaving the judges with an unenviable task to come up with a winner.
Hamilton had started well before Yorkshireman Woodhouse came on strong from the second round onwards, enjoying particular success when he attacked the body.
Both fighters were looking to set up their right hand but neither ever looked capable of a stoppage.
Hamilton had some of his best moments in the eighth, pinning his opponent against the ropes with a barrage to the body.
Understandably given the relentless pace, both men slowed slightly in the closing rounds; Woodhouse enjoyed the better of the 11th and the Hamilton doing likewise in the 12th.
Hamilton, whose record now drops to 14-3, took the decision graciously: "It could have gone either way. He had the advantage of being at home. It was a close fight. As the champion I should have dominated a lot more."