Daley and Lee finished 48 points clear of Mexico’s Randal Willars Valdez and Ivan Garcia Navarro in a score that would have won silver at the 2019 World Championships.
It was Daley’s 33rd career gold medal and his first at the World Cup, having won bronze in Beijing in 2008 and Rio in 2016 in the lead-up to his first and third Games.
Team GB will be represented in every diving discipline for the fourth successive Games as quota places were wrapped up in women’s 3m springboard and 10m platform.
Lois Toulson and Eden Cheng took overall silver behind Canada to secure an Olympic place for their nation, producing the best dive in the field in the third round having sat seventh.