Ed McKeever enjoyed a successful return to the Polish course where he won a 2010 world title, taking gold at the opening Sprint World Cup of 2011.
McKeever triumphed again in the kayak single (K1) 200m event in Poznan.
"It's nice to start where I finished last year, being in the same location and gaining the same result," he said.
Fellow Brits Liam Heath and Jon Schofield came a creditable second, behind world champions Arnaud Hybois and Sebastien Jouve in the K2 200m.
GB Canoeing head coach Brendan Purcell said the results at the season's first big event made for an encouraging start.
"Ed just did the job. He is a very professional elite athlete and has proved he can deliver performance after performance" said Purcell.
"It was an exciting race in the K2 200m between us and the French. The boys feel they didn't quite get their best race out but they demonstrated that they are very competitive."
Sunday's medals are a step up from Saturday's performance, where British contestants reached two finals but failed to win any medals.
In the four-man kayak (K4) 1000m final, the new combination of Olympic champion Tim Brabants, Ben Farrell, Paul Wycherley and Andrew Daniels finished eighth.
In the K2 1000m final, Wycherley teamed up with Jon Boyton for the first time, coming home in sixth place.
"Jon and Paul had a strong performance; they just couldn't quite hold their pace but have lots of positives to take away," said Purcell.
"It was the first international race for the K4 and we now have some key areas for the coaches and athletes to go away and work on. We just need to build over the next couple of regattas."
Brabants, who is just returning from injury, failed to reach the final in the K1 1000m, the event in which he won Olympic gold in Beijing.