The 23-year-old former Golf Australia National Squad member will make his debut among the paid ranks in this week's Thailand Golf Championship at Amata Spring Country Club.
"My dream as a young boy was to turn pro eventually and I am absolutely delighted that this day has arrived," said Watt, who reached world number one status in the amateur ranks last June.
"I am following in some huge golfing footsteps and I just hope I can give Australia somebody else to be proud of. I would like to extend my thanks to Golf Australia and Golf WA who have provided significant support to me during my amateur career."
Watt, who was the medallist at this year's U.S Amateur, will make the transition to the professional ranks guided and helped by International Sports Management. Andrew "˜Chubby' Chandler, ISM's Chief Executive Officer, said: "Brady is not only an incredible young golfer, but also a great guy and to finish 14th at the Australian Open was very impressive. He is a very strong player and I can't wait to see what the future holds."
Born in Perth, Watt enjoyed a glittering amateur career. Among its highlights was a debut semi-final placing at the U.S Amateur Championship in August.
Other notable performances included winning the Lake Macquarie Amateur in 2011 and Riversdale Cup and Australian Amateur Stroke Play in 2013.
He also won the 2012 Keperra Bowl in Brisbane and finished runner-up to fellow West Australian Oliver Goss at the 2012 West Australian Open.
He was also a member of the triumphant Australian Ten Nations Cup side in February before being added to the Golf Australia National Squad.
Golf Australia High Performance Director Brad James said "Brady has had a terrific year and is ready for this move. Golf Australia will continue to work with Brady through our Rookie Professional program which is specifically designed to support players as they make this transition."
Watt has been coached for much of his amateur career by Perth based Craig Bishop.
Having missed out at Stage Two of the recent Web.Com Tour qualifying, Watt will attend the 2014 Asian Tour School, but hopes to attract invitations to play globally.
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