The 27-year-old, who missed the first three events of the season due to an ankle injury, sprinted away to beat rival Javier Gomez with Frenchman Vincent Luis in third.
Brownlee led into transition at the end of the cycling stage but dropped off the leading group after his trip and had to fight his way back into contention.
Brownlee said: “I knew I wasn’t that fit, I didn’t have good legs to be honest, then Javier tripped me up and I had to run back so the whole thing was tough.
“I should only get fitter from here so give me another three weeks and hopefully I will be another notch up.”
Brownlee’s brother Jonny missed the event to concentrate on the upcoming triathlon Test event in Rio which could count towards qualification for next year’s Olympic Games.
Brownlee’s victory capped a good week for Great Britain after Vicky Holland triumphed in the women’s race on Saturday.
Holland, who won bronze for England at last year’s Games, had to miss the opening races of the new triathlon season.
But she was back on Saturday, finishing ahead of America’s series leader Katie Zaferes and Switzerland’s Nicola Spirig.