La Roja were drawn into a battle by Lionel Messi and Co in New Jersey and Luis de la Fuente needed another goal off the bench to claim victory.
Arsenal midfielder Mikel Merino had scored winners against Portugal and Belgium as a substitute in the earlier knockout rounds and Torres was handed a similar challenge after replacing Mikel Oyarzabal on the hour mark.
The Barcelona forward had only started one game at the 2026 tournament, with no goals scored, but he rose to the challenge with perfect timing for his country.
Despite being criticised for his lack of output at the World Cup, Torres was hailed by his manager after the final, and defender Pedro Porro believes his goal was the perfect response to his doubters.
"His mentality is spectacular. He works incredibly hard both at Barca and here with us. Some people have been very unfair to him, and I think his mentality of continuing to work, and improve every day, now life has rewarded him.
"It's led him to score the goal that gives us a World Cup and I only have words of gratitude for him because he's a kid who deserves it."