The 19-year-old Lyon forward headed home bravely from close range in the 85th minute to complete a stirring comeback that restored some gloss to French football after the miserable end to the senior side's 2010 FIFA World Cup™ campaign.
"It's magic, it's magnificent!" said France striker Cedric Bakambu, who finished the tournament with three goals. "For the second half, we told ourselves that we had nothing more to lose. We're at home, we'll give everything. Most of all, the fans were with us, and it was fantastic."
Spain had played superb football throughout the tournament and dominated the first half, taking an 18th-minute lead when Rodrigo ran onto Daniel Pacheco's fine through-ball and coolly slotted the ball into the bottom-right corner.
Francis Smerecki's France team barely mustered a shot at goal in the first period but after weathering early pressure in the second half, they conjured an unexpected equaliser.
Arsenal starlet Gilles Sunu headed a high ball into the path of Yannis Tafer and then raced through to receive Tafer's return pass before lobbing the ball over Spanish goalkeeper Alex.
In the image of the senior team that secured their first ever FIFA World Cup title in South Africa earlier in the month, Spain monopolised possession for long periods but found themselves repeatedly exposed on the break.
Tafer could have given France victory with 10 minutes remaining when he broke free ut saw his powerful left-foot shot pushed away by Alex.
The winning goal arrived just five minutes later though, when Chelsea forward Gael Kakuta, a contender for player of the tournament, sparked panic in the Spanish defence with a direct, mazy run and when his effort was parried by Alex, he centred smartly for Lacazette to score.