The three ads, "hungover", "big meeting" and "split up", display collections of the museum's art tailored to specific personal circumstances.
The work beat competition from the gold-winning TBWA\Whybin in Auckland for Adidas "be the ball" and BBDO Argentina for Nike "feet-hands".
A campaign from Shout Gothenburg, which highlighted the number of homeless people in Sweden, was also marked as an "amazing idea" but could not be considered for the Grand Prix because it was a government campaign.
Fernando Vega Olmos, the president of the Outdoor jury and the Unilever worldwide creative director at Lowe, said: "I'm very proud of the standard of all our gold winners but the Tate campaign was such a strong contender because it's such a powerful idea and modern communication. It connects art with everyday life and really changes the way you can experience it."