Current club Wycombe Wanderers announced the news on Tuesday, with the centre-back hanging up his boots due to an ongoing knee problem.
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Mawson played top flight football for Swansea and Fulham and was called up to the senior Three Lions squad in 2018.
Although he didn't play, he did made six appearances for England Under-21s. He was also linked with transfers to Liverpool, Arsenal and Tottenham during the pomp of his career.
The defender ends his playing career having made over 250 appearances across the top six tiers of English football, including 80 in the Premier League.
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He also earned two promotions, having won the League One play-off final with Barnsley in the 2015/2016 season, and also lifting the Football League Trophy the same campaign.
Coming through the Brentford academy, Mawson actually began his professional Football League career with Wycombe having joined them on loan from the Bees in 2014/15.
He rejoined the Chairboys last summer, with his final appearance coming against Ipswich in December, and the centre-back is set to get a send-off from fans when Wanderers take on his former club Barnsley at Adams Park on March 18.
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Mawson said on wwfc.com: "It might come as a shock to some people but, to me, it's been coming for a while.
"I had some time off around Christmas after feeling some pain in my knee and the pain hasn't gone away. I went for a scan and unfortunately the damage was done.
"It's devastating, but it's how life goes. I was nearly in this situation in the summer, and I'd fallen out of love with the game. I think, if I'd retired then, I wouldn't have wanted to even watch football again. But coming back here has made me fall back in love with it.
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"I knew this day was going to come - it's just sooner than I had hoped. But there's a lot worse things going on in the world and that makes you realise that, at the end of the day, it's a job."
Wycombe boss Gareth Ainsworth praised Mawson, saying: "I'm immensely proud to have worked with Alfie at the start and now what has sadly proved to be the end of his playing career, and what a journey he has had.
"We always knew in those early days that he had the ability and the character to be able to play at the highest level, and he worked so hard to achieve his dream."