The 10-second spot launches on Friday and features an animation of a gymnast performing a move and receiving a cheer.
It introduces the strapline "Great moments last forever".
The ad, which has been created in-house, runs across ITV2 and E4 until 12 August.
It will be supported by an outdoor campaign, running on the London Underground and a direct response campaign. The media was handled by MediaVest.
In addition Yahoo will be placing sponsored links next to stories on other sports sites, to promote its own sports coverage.
Yahoo has bumped up its investment in sports in recent years through its partnership with Eurosport, including winning the exclusive online rights to Premier League highlights.
While Yahoo will not be showing TV footage from the London 2012 Olympics it will offer news coverage on a sports hub.
Robert Bridge, head of marketing at Yahoo EMEA, said: "Yahoo has seen heavy investment in premium sport content in recent years and has built up an extensive audience to offer the number one commercial sports site in the UK.
"This campaign is designed to continue to build the Yahoo brand and its association with premium content around major sporting events, furthering its market leading position in sport."
The last TV activity Yahoo ran was for its $100m 'It's You!' revamp in September 2009.
Yahoo has recently appointed Google veteran Marissa Mayer as its new chief executive, while its UK business has undergone a restructure.Follow @shearmans