Britain's Ben Saxton and Katie Dabson finished narrowly ahead of closest rivals Fernando Echavarri and Tara Pacheco in the final race to win the Nacra 17 World Championship.
The Britons, who began the day with a four-point lead, came second in Sunday's medal race to secure the title.
Echavarri and Pacheco's third place saw them take overall silver.
"It's unbelievable. It's every dream come true," said Rio Olympian Saxton.
"Well done to Katie, and thanks to our coaches Hugh and Derek and to National Lottery funding from back at home. It's awesome."
The medal race was disrupted briefly by a collision between Italy's Ruggero Tita and Caterina Banti - who took overall bronze - and Spain's Iker Martinez and Olga Maslivets.
Saxton and Dabson eventually finished second behind Germany's Paul Kohlhoff and Alica Stuhlemmer, narrowly in front of closest rivals Echavarri and Pacheco.
The Nacra 17 was built to be sailed by mixed-gender crews and made its Olympic debut at Rio 2016.
1. Ben Saxton and Katie Dabson (GB) 92 points
2. Fernando Echavarri and Tara Pacheco (Spa) 95
3. Ruggero Tita and Caterina Banti (Ita) 109
4. Gemma Jones and Jason Sauners (NZ) 111
5. Paul Kohlhoff and Alica Stuhlemmer (Ger) 115