Top spot went to American singer Kesha's debut release 'Tik Tok' with more than double that - 12.8 million copies.
Although the digital market increased by 6% bosses are still blaming illegal downloads for it not being bigger.
IFPI chief executive Frances Moore said:
"As we enter 2011, digital piracy, and the lack of adequate legal tools to fight it, remains the biggest threat to the future of creative industries.
"Great new legitimate music offerings exist all over the world, offering consumers a wide range of ways to access music.
"Yet they operate in a market that is rigged by piracy, and they will not survive if action is not taken to address this fundamental problem. This is the challenge and the opportunity for governments to seize in 2011."
The top 10 digital singles in the world in 2010 were:
1. Tik Tok by Kesha sold 12.8 million copies.
2. Bad Romance by Lady Gaga sold 9.7 million copies.
3. Love The Way You Lie by Eminem featuring Rihanna sold 9.3 million copies.
4. Telephone by Lady Gaga sold 7.4 million copies.
5. OMG by Usher featuring Will.i.am sold 6.9 million copies.
6. California Gurls by Katy Perry sold 6.7 million copies.
7. Hey, Soul Sister by Train sold 6.6 million copies.
8. Baby by Justin Bieber sold 6.4 million copies.
9. I Gotta Feeling by Black Eyed Peas sold 6.1 million copies.
10. crushcrushcrush by Paramore sold 6.1 million copies.
