The campaign, through M&C Saatchi, which breaks in London cinemas this Friday, is the first broadcast work on the account by the agency since it won the business in 2001.
The campaign is intended to build on the Department of Transport's work in encouraging motorcyclists to ride more defensively and to urge riders and drivers to look out for each other.
Marc Catchpole, a senior executive at Transport for London, said: "In response to the specific problem we are seeing in London, we felt we needed to speak directly to motorcyclists about the importance of defensive riding yet leave a clear take-out for drivers to look out for powered two-wheel riders."
PHD is handling media planning and buying for the advertising, which is in response to the relentless rise in motorcyclist deaths. This runs counter to the falling numbers of road deaths in London.
Death and serious injuries among riders of two-wheel vehicles, including motorbikes, scooters and mopeds, have risen constantly since 1995.
The commercial dramatises the message by showing a motorcyclist being hurled into the air after hitting an apparently invisible object. A voiceover says: "This motorcyclist never knew what hit him," and warns: "Look out for the driver who didn't see you." The ad was written by Kit Dayaram, art directed by Colleen Phillips and directed by Syd Macartney for 2am Films.
Paul Hodgkinson, the M&C Saatchi deputy creative director, said: "The ad forces drivers to consider their every move and motorcyclists to ride defensively."