Apple Computers reported that it reached the billion-song threshold at its globally popular iTunes online music store, an AFP report said.
The report said the billionth song officially sold was "Speed of Sound" by the British band Coldplay and was downloaded by a man in the US state of Michigan.
The AFP report quoted Apple chief Steve Jobs as saying that "I hope that every customer, artist and music company executive takes a moment today to reflect on what we've achieved together during the past three years."
Industry reports said Apple's iTunes store had been the major source of audio and video downloads for the market-leading iPod.
According to Apple, iTunes had also sold more than 15 million videos.