Williams, who scoops the title after becoming runner-up in 2011, beat Joe Mccafferty and Paul Matthews who finished in second and third place respectively.
The chef and restaurateur now joins an elite list of former winners of the prestigious Craft Guild of Chefs prize including Gordon Ramsay, Simon Hulstone, Mark Sargeant and, most recently, Frederick Forster.
"I've had a lot of good things happen in the last month and its all been down to many years of hard work," Williams said, speaking to BigHospitality just after the results were announced.
Before opening his eponymous Mayfair eatery last year Williams cooked in various other restaurants around the world and spent a number of years working for Marcus Wareing.
However in the last month he has seen his new venture scoop a first Michelin star and make the top 20 in the National Restaurant Awards. Now the chef has won this individual prize which he said topped the lot.
"I've worked in some tough kitchens over the years. I've got a bloody good team behind me so I would like to thank them for their support and my wife who has stuck with me through thick and thin."
BigHospitality managed to get the first word with Alyn Williams following the announcement of his win after his exploits in the Competition Theatre at Earls Court 2. For his reaction in full watch the exclusive video below:
Alongside the seven other finalists, the popular chef was tasked with producing a three course menu in two hours using a selection of ingredients chosen from a mystery basket. The basket was presented to the eight chefs at a mentor's day earlier this year where they were also given some last-minute advice.
Williams, who put the secret of his success down to three 'consistently strong' dishes, prepared a menu including a starter of fillets of mackerel, saddle of venison main and caramelised white chocolate panna cotta to finish.
Phil Howard, chef and co-owner of The Square restaurant and winner of the Chef's Chef of the Year at the National Restaurant Awards, led the team of judges - Gary Hunter, Angela Hartnett, Atul Kochhar, Mark Sargeant, Tom Kerridge, Henry Brosi, Paul Gayler, William Curley, Daniel Clifford and Lou Jones.
In a speech at the winners' ceremony Howard praised the standard of the annual competition in his first year as chair of the judges saying only fellow chefs could truly understand the pressures of this unique challenge.
As well as the renowned title, Williams takes a prize package worth more than £15k back to his Mayfair kitchen - the list of prizes includes cash, a dinner and study trip in France, a study tip to Norway, a number of master classes plus products and equipment.
The eight finalists were:
Andrew Wright, Restaurant 23
Alyn Williams, Alyn Williams at The Westbury
Joe Mccafferty, Chrysan Restaurant
Paul Dunstane, Restaurant Associates
John Howie, Sodexo Prestige
Paul Matthews, The Hunter S Restaurant
Justin Galea, Turnberry Hotel
Hayden Groves, BaxterStorey