James Peters and Fynn Sterritt defended their 49er title at the Hemel World Cup Series in Enoshima, Japan.
The duo started the day in fifth overall but staged a remarkable comeback which saw them finish second in the medal race.
Fortune was with the Brits as the German team of Tim Fischer and Fabian Graf capsized when they were in control of the race leaving the door open.
Retaining their title was one of the best moments of his life according to Sterritt, 30, who still had belief heading into the medal race.
“We really wanted to defend our title from last year,” Sterritt said.
“Going into the medal race it didn’t look like we were going to do it, even though it was mathematically possible.
“It takes a lot to pull these kind of things off when there are so many boats involved to stand a chance.
“The stars aligned and we’ll take it. Unbelievably happy and this is probably one of the best moments of my sailing career so far.”
Britain had more medal success at the home of the Tokyo 2020 Olympic sailing regatta, as Ben Saxton and Nikki Boniface claimed Nacra 17 silver.
The pair led heading into the final day but could only finish fifth in the medal race leaving the French duo Quentin Delapierre and Manon Audinet to win the race and secure gold.
Saxton, 29, acknowledged the team made a tactical error which ended their hopes of gold but they were happy to still be on the podium.
“I’m really happy with the way we sailed in the fleet racing,” Saxton said.
“I think we obliterated that, especially if you take it without a discard we were a league clear of everyone else.
“We actually sailed quite well today but on a short course like we had you live or die by your first decision and we left ourselves with a bit to do.
“We had to comeback, we did that well to save the second, but overall I am happy with how we sailed.”
John Gimson and Anna Burnet finished fifth in the Nacra 17 while windsurfers Emma Wilson and Tom Squires both also ended up fifth overall in their regattas.