This is a list of songs that reached the number-one position on Billboard's Adult Top 40 (formerly Hot Adult Top 40 Tracks) chart in 2009:
| Issue Date | Song | Artist |
|---|---|---|
| January 3 | "Hot n Cold" | Katy Perry |
| January 10 | ||
| January 17 | ||
| January 24 | "Gotta Be Somebody" | Nickelback |
| January 31 | ||
| February 7 | ||
| February 14 | ||
| February 21 | ||
| February 28 | "You Found Me" | The Fray |
| March 7 | ||
| March 14 | ||
| March 21 | ||
| March 28 | ||
| April 4 | ||
| April 11 | ||
| April 18 | "Sober" | Pink |
| April 25 | "You Found Me" | The Fray |
| May 2 | ||
| May 9 | ||
| May 16 | ||
| May 23 | "Gives You Hell" | The All American Rejects |
| May 30 | ||
| June 6 | ||
| June 13 | "You Found Me" | The Fray |
| June 20 | "Second Chance" | Shinedown |
| June 27 | ||
| July 4 | ||
| July 11 | ||
| July 18 | ||
| July 25 | ||
| August 1 | ||
| August 8 | "Her Diamonds" | Rob Thomas |
| August 15 | ||
| August 22 | ||
| August 29 | ||
| September 5 | "No Surprise" | Daughtry |
| September 12 | ||
| September 19 | "Use Somebody" | Kings of Leon |
| September 26 | ||
| October 3 | ||
| October 10 | ||
| October 17 | ||
| October 24 | ||
| October 31 | ||
| November 7 | ||
| November 14 | ||
| November 21 | ||
| November 28 | ||
| December 5 | "Already Gone" | Kelly Clarkson |
| December 12 | ||
| December 19 | ||
| December 26 |
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