The 24-year-old was able to claim the title before the final stage in Hawaii in December
"My whole life has gone toward this. I can't believe I'm the world champion. That was my goal. This is my dream. I'm so stoked," he said.
The 24-year-old had advanced to the finals of the Portugal Pro event held off the coast of Peniche in central Portugal with a win over California's Kolohe Andino.
He was able to claim the title before the final stage in Hawaii in December after Smith -- the only rival with enough points to beat him -- was defeated by Conner Coffin of the United States.
Florence won the final of the Portugal competition against Coffin, scoring 16.67 points to his rival's 9.93.
He finished in first in the overall classification with 56,400 points, followed by Brazil's Gabriel Medina who had 45,450 points and Smith with 41,700 points.
Florence will now head to his home event, the Pipe Masters in Oahu, with the world title safely in tow.
"To win it here and not have the stress of taking it to Pipe, it's pretty good. I get to relax and surf my favourite wave in the world."
He is the fourth Hawaiian ever to win a world title after Derek Ho in 1993, Sunny Garcia in 2000 and Andy Irons in 2002, 2003 and 2004.