The DfT said 86,722 of the votes were cast for the winning ad, which was created by the youngest team to make the three-strong shortlist. The strategy behind the competition was devised by the DfT's media agency of record, Carat.
Called "ghost", the winning ad was created by 13-year olds George Sampson from Warrington, Vanessa Uanseru from Southwark, and Anya Fitzpatrick from Glasgow.
The spot features a teenager crossing a road without looking because he is listening to loud music on a MP3 player.
As the boy crosses the road he spots the ghosts of three other teenagers who were killed walking across the same road, for failing to pay attention to an uncoming vehicle.
A car drives through their ghostly appearances, which stops the boy walking into the path of the same car.
He then finds a safe place to cross the road at a set of traffic lights. It ends with the strapline: "Think! Give the road your full attention."
The ad will now become the official TV ad of the "Think!" campaign and will break across the MTV network on August 6.
The Department for Transport launched the contest to promote its 'Think!' road safety initiative in February, in conjunction with Viacom Brand Solutions.
Last week the three shortlisted entries were run on MTV and viewers were invited to choose the winner by submitting a vote online.