Brownlee, 22, finished behind Olympic silver medallist Javier Gomez in the world series grand final, but that was enough to pip the Spaniard in the overall rankings.
Brownlee’s elder brother Alistair, the Olympic champion, missed the final after undergoing an appendix operation and was out of the running after skipping several earlier races through injury.
"To keep the title in the family is pretty special," Brownlee said. "It's been a great year more than anything.
"If at the start of the year, someone said that Alistair would be Olympic champion, and I would be Olympic bronze medallist and world champion as well, I would definitely have taken that."
Russia’s Dmitry Polyanskiy came seventh on the day to finish third in the overall standings.