The US chart company crowned the Bajan star just seven years into her career, which has produced numerous entries on the Pop Songs Chart list.
Rihanna has had 34 songs chart on the weekly countdown since her 2005 debut 'Pon De Replay', including nine number ones and 21 Top 10 hits.
"Billboard crowned me #1 top 40 artist of the decade just 7 years into this!!" Rihanna tweeted. "My fans just majorly s**t on ur existence. #HistoRIH."
Pink landed in second place, while Britney Spears followed at three and Kelly Clarkson at four.
Katy Perry, Beyoncé, Lady GaGa and Chris Brown are among the other names to feature in Billboard's Top 40 Pop Songs Chart artists of the past two decades.
Earlier today, it was confirmed that Rihanna has overtaken Eminem to become the most-liked person on Facebook, with just under 62 million fans.
Billboard Top Pop Songs Artists 1992-2012 Top 20:
3. Britney Spears
4. Kelly Clarkson
5. Mariah Carey
6. Katy Perry
8. Black Eyed Peas
9. Janet Jackson
11. Lady GaGa
12. Christina Aguilera
13. Justin Timberlake
15. Matchbox 20
17. Backstreet Boys
18. Jennifer Lopez
19. Maroon 5
20. Avril Lavigne
Listen to Rihanna's new single 'Diamonds' below: