Travellers who use Oyster's online auto top-up facility will be given the opportunity to download five free songs from the iTunes Store, which now offers about 5m tracks.
The partnership will be supported by online and offline marketing communications created by Chemistry. The work will include press and 48-sheet posters, as well as ads on buses and the London Underground.
The campaign, which will run until the end of February, adapts the names of London Tube stations to resemble those of famous musicians such as Eric Clapham, Lily Balham and Whitney Euston. The ads will drive Oyster-card users to a dedicated microsite, tfl.gov.uk/itunes, where they will be asked to enter a promotional code enabling them to download the free songs.