The siblings, who were confirmed in Great Britain's Olympic team just a few hours before the race, worked together in the bike and run and crossed the line together too.
It's Jonathan's third successive victory - after wins in World Championship Series races in San Diego and Madrid - while just coming through the race meant more to Alistair, who has spent the season watching his brother's impressive performances while recovering from an Achilles tear.
"It's good to be back racing," said Alistair, who will test his injury further in his first World Triathlon Series race of the season in Kitzbuhel in two weeks' time.
"When you've had an injury you're never quite sure how it's going to respond.
"You can train on it but racing is different. It's nice to come and do a race and it be all right."