Conlan, 34, announced his retirement immediately after the fight.

"It’s the end of the road for me," Conlan said in his dressing room. "I said the next defeat, no matter the situation, no matter the circumstances, that would be me finishing boxing. And it has come. I didn’t think I lost, but it wasn’t good enough. And that’s a simple fact. Thirty-four, probably too long in the tooth.

"I thought I won, but it is what it is. I don’t want to do it anymore. It’s time to say goodbye to boxing."

Meanwhile, Walsh (20-0, 10 KOs) was delighted with the result, which gives his career a tremendous boost.

“I was very confident I got the job done, to be honest,” he said after the fight. “I mean, it was definitely a close fight. Shout out to Mick Conlan. I've always been a fan of him, but I knew I got the job done. It was hard for him to figure me out, honestly. He's a hell of a fighter, but his time's up, baby.”

Before the fight, Conlan (20-4, 10 KOs) acknowledged that although he was entering the final phase of his career, he was as determined as ever to become a world champion. However, the 34-year-old allowed Walsh to pick his pocket during a dull, low output fight.

Although he was stepping up a number of levels, the charismatic 33-year-old from Brockton, Massachusetts, carried himself with confidence throughout the various fight week set pieces, and his belief was bolstered when a hard left hook found Conlan’s chin as the opening round drew to a close.

Cut on the hairline after a clash of heads, Conlan took the center of the ring but struggled to find his range or land regularly. Walsh seemed lost whenever Conlan switched southpaw, but upped his output whenever the home favorite switched back to orthodox.

Meaningful punches were few and far between.

Given the vast gap in experience between the two, it was unsurprising that Walsh struggled to find openings but Conlan’s inability to land consistently was surprising. The former amateur world champion and Olympic bronze medallist pawed with his jab, controlled the tempo of the fight and stayed defensively aware, but seemed wary of letting his hands go.

It felt as if Walsh’s big chance was steadily slipping away.

Realizing that Walsh was running out of ideas, Conlan briefly upped the tempo in the seventh and the two engaged in a rare exchange. Nothing meaningful landed, apart from a leg kick from Walsh, who lashed out through frustration.

Considering so few punches had landed, Conlan’s face was marked up. As the blood continued to stream down his face, he also began to bleed from a cut over his right eye in the eighth.

A window of opportunity briefly opened for Walsh in the ninth. As Conlan allowed his back to touch the ropes for almost the first time in the fight, Walsh landed a pair of hard left hooks, but chose to smile and pound his chest rather than try to press home his advantage.

Apart from one all-or-nothing assault from Walsh, the 10th passed without incident, but Walsh’s short sharp bursts of aggression had clearly impressed the judges, and he was awarded a life changing decision.

The scores were 96-94, 96-94 and 93-97.

Conlan had started to make noises about a fight with New York’s WBC featherweight title holder Bruce “Shu-Shu" Carrington, but he will now have to make some serious decisions about his future.

After hearing the decision, Walsh took his chance to call out his fellow American.

“Shu-Shu, where you at, baby?” he said. “Let's go. Give me my shot, baby. Come on. You're a hell of a fighter, but it's my turn, baby.”

In the evening’s chief support bout, Kieran Molloy (14-0, 7 KOs) boxed this way to a clear unanimous decision victory over Xavier Kohlen (15-3-1, 7 KOs).

The unbeaten Irishman always held the upper hand, but the stubborn Dutchman refused to go away. Molloy was far better technically than Kohlen, but although the scorecards were wide, he hard to work for his victory. The scores were 99-91, 100-90 and 98-92.