Just 24 hours after team-mate Helen Jenkins won the women's race, the brother of two-time world champion Alistair kicked away from Switzerland's Sven Riederer and South Africa's Richard Murray to clock one hour, 48 minutes and 47 seconds.
This summer Brownlee was expected to play a supporting role to his brother, who is currently sidelined by an Achilles tendon injury and is not planning to return to action until June's World Triathlon Series race in Kitzbuehel.
However, on this evidence the double world sprint champion should be a serious contender to his sibling.
In contrast to his brother, who is aiding his recovery by training on an underwater treadmill at the home they share in Yorkshire, Jonathan Brownlee has enjoyed his best-ever off-season and it showed.
He started to impose himself on the race when he got into a small break on the bike leg and by the time the run was winding up to a conclusion he was in pole position and primed to strike, with a sudden injection of late pace that has become a family trademark.
"For me it was the first race of the season, I didn't really know what to expect," said Brownlee.
"Seven months is a long time out, I was in a bit of shock at the race briefing thinking wow, 'It's been a long long time since I've been in one of these'. I went into the race very relaxed really because I knew I didn't have to do anything, I didn't have to finish top nine, top four or anything, I just had to race my own race.
"The swim and the bike were good, I wasn't sure what to expect on that, but I have been running well all winter and my cross country races have been good. I felt good on the run. I felt a bit tired towards the end, I think I lacked a bit of racing there.
"Sven Riederer is a tough guy, he's chased me down a few times before, in Beijing he chased me down down and he never gives up.
"So it was a good race, it shows that the training has gone well over the winter and I'm looking forward to the next race really."
Meanwhile, with the Brownlees considered a lock for two of the three available British men's places at the Olympics, team-mate Tim Don, himself a former world champion, made his case for the remaining slot with a solid seventh place finish.