Picon had already been guaranteed her gold medal in Santander going into the final day of racing in the class, while Bontemps still had work to do to get over the line.
However, Olympic silver medallist Bontemps kept his cool to move 21 points clear at the top of the standings - while Picon also built on her advantage to sit 40 points in front after another day of challenging wind conditions.
Bontemps proved too strong for Przemyslaw Miarczynski of Poland, who finished second, while France's Thomas Goyard was a place further back in third.
Experienced Spaniard Marina Alabau proved to be Picon's closest rival with Israel's Maayan Davidovich taking bronze.
"I'm really happy to win this title, it's really amazing," Bontemps told La Parisien.
"Sea conditions were very different this week. We had to be versatile but I'm happy because I've been very consistent, my worst race was a seventh place.
"I really gained momentum during the week to pick up this title. The medal race was really nice, and more so with the audience, it was great and I felt really good."
With both Lasers classes wrapped up yesterday by Marit Bouwmeester and Nicholas Heiner, the next medals will be handed out tomorrow in the 470 events.
Australian pair Mat Belcher and Will Ryan occupy a dominant position in the men's standings, leading Croatian competitors Sime Fantela and Igor Marenic by 14.7 points going into Saturday's sailing.
In the women's 470, everything remains finely poised with Australia and New Zealand separated by only a point at the summit.
With two races remaining on Saturday Lara Vadlau and Jolanta Ogar will hope to keep Jo Aleh and Polly Powrie at bay.
An aside in the 470 events saw 23 spots for the Rio 2016 Olympics picked up with Austria, China, France, Great Britain, Japan, Netherlands, New Zealand, Russia Slovenia and the United States booking places in the women's competitions.
In the men's side, Australia, Austria, Croatia, Spain, France, Great Britain, Greece, Japan, New Zealand, Russia, Switzerland, Sweden and the US followed suit.
The men's 49er, women's 49erFX and Nacra 17 classes all have one day remaining before the medals are handed out.
In the former, Peter Burling and Blair Tuke of New Zealand occupy pole position while Danish pair Ida Marie Baad Nielsen and Marie Thusgaard Olsen lead the 49erFX standings.
French pair Billy Besson and Marie Riou lead the Nacra 17 standings by 25 points going into the final two days of racing, with Argentina's Santiago Lange and Cecilia Carranaz Saroli the closest threat.