Spieth, 21, played his best golf ever to take the crown by six shots, recording a career-best eight-under-par 63 in poor conditions at the Australian Golf Club.
This left Spieth, pictured here wearing a blue golf shirt , 13 under overall.
Eight birdies, four on each half of his card, was testament to the American's consistency.
Not once did he look like surrendering the three-stroke lead he had built up at the halfway point.
Spieth saw off Rory McIlroy, who had early on in the tournament threatened to defend the crown he had secured at last year's Royal Sydney event.
McIlroy fell away in the second half of the Open, following Saturday's 76 with 72 on Sunday to end 15 shots off Spieth.
Superb putting maintained the Irishman's par on holes two and four. But his challenge effectively ended on the fifth when he bogeyed, despite a magnificent tee shot.
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