The track, which rises from two to one, matches Madonna's tally of chart-topping singles and places her joint-fourth for the most number ones in US chart history.
Elsewhere, Maroon 5's 'One More Night' slips one to two and Ke$ha holds at three for a second week with 'Die Young'.
Bruno Mars lifts six to four with 'Locked Out Of Heaven' - marking his eighth top five hit - while The Lumineers jump 13 to eight and Flo Rida's 'I Cry' completes the top ten.
Further down the chart, Kendrick Lamar reaches a new peak at 19 with 'Swimming Pools (Drank)', Justin Bieber and Nicki Minaj leap 38 to 20 with 'Beauty and a Beat' and Adele's 'Skyfall' rebounds 33 to 21.
Swedish House Mafia vault 48 to 33 with 'Don't You Worry Child', Frank Ocean's 'Thinkin Bout You' rebounds 43 to 35, and One Direction debut at 41 with 'Little Things'.
Elsewhere, Pink leaps 69 to 50 with 'Try', Christina Perri lands at 67 with 'A Thousand Years (Part 2)', and The Weeknd's 'Wicked Games' climbs 91 to 81.
The top ten singles are as follows (click where possible for our reviews):
1. (2) Rihanna: 'Diamonds'
2. (1) Maroon 5: 'One More Night'
3. (3) Ke$ha: 'Die Young'
4. (6) Bruno Mars: 'Locked Out of Heaven'
5. (4) fun.: 'Some Nights'
6. (8) Ne-Yo: 'Let Me Love You (Until You Learn To Love Yourself)'
7. (5) Psy: 'Gangnam Style'
8. (13) The Lumineers: 'Ho Hey'
9. (7) Taylor Swift: 'We Are Never Ever Getting Back Together'
10. (10) Flo Rida: 'I Cry'
Watch Rihanna's 'Diamonds' video below: