"I was going to give it everything and I was delighted with how the race went."
Brownlee, the former junior and under-23 world champion, finished in an official time of 1 hour, 44 minutes and 51 seconds.
Gomez was second, while Beijing Olympic gold medallist Jan Frodeno of Germany finished third.
"That run leg nearly killed me," said Brownlee, who has won four of the seven World Championship Series events this year.
"I just went on and on and at the end went for it."
The race - held in perfect temperatures of about 20C (68F) at the tourist resort - included a 1.5-kilometre swim leg in the Nerang River, a 40-kilometre cycle route and a 10-kilometre run.
Brownlee is exhausted as he crosses the line for victory
Brownlee clinched the overall title with 4,400 points - 800 from each of his previous series wins and the 1,200 for the final.
Gomez was second overall with 3,959, followed by Saturday's fourth-placed finisher, Maik Petzold of Germany, with 3,442 and Frodeno in fourth overall with 3,162.
Brownlee's fellow Britons Will Clarke and Tim Don finished the race in 11th and 16th respectively.
Meanwhile, Brownlee's younger brother Jonathan, 19, finished second in the junior men's competition on Sunday while Hollie Avil won the women's under-23 title on Friday with fellow Brits Jodie Stimpson and Vicky Holland finishing second and fourth respectively.
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