Tyler Wright of Australia was eliminated by fellow Aussie Sally Fitzgibbons in the quarterfinals at Guincho Beach.
Moore, 19, officially claimed the season crown during Saturday's semifinal heat against American Sage Erickson and went on to win the Cascals title by topping Fitzgibbons in the finals by a score of 10.44-9.70.
It is her fourth win on the Association of Surfing Professionals women's tour.
"Conditions got tough there in the end -- no doubt," Moore said. "I was still riding the high of clinching the world title and I think that momentum helped me push through in the end."
Wright was second in the ASP point standings at the end of the day. Fitzgibbons was in third place.
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