This lists songs that hit number one on the charts in the US during 2005. If a song spent nonconsecutive weeks at number one, the number of weeks for each occurrence at the top is shown in parenthesis.
| Date | Artist - Title | Weeks at #1 |
| December 26 2004 – February 26 2005 | Mario - Let Me Love You | 9 |
| February 27 – April 30 2005 | 50 Cent feat. Olivia - Candy Shop | 9 |
| May 1 – 28 2005 | Gwen Stefani - Hollaback Girl | 4 |
| May 29 – June 25 2005 | Mariah Carey - We Belong Together | 14 (4) |
| June 26 – July 2 2005 | Carrie Underwood - Inside Your Heaven | 1 |
| July 3 – September 10 2005 | Mariah Carey - We Belong Together | 14 (10) |
| September 11 – November 19 2005 | Kanye West feat. Jamie Foxx - Gold Digger | 10 |
| November 20 – December 24 2005 | Chris Brown - Run It! | 5 |
| December 25 2005 – January 7 2006 | Mariah Carey - Don't Forget About Us | 2 |
8 different songs hit number one in the US during 2005.
Top 5 Songs of 2005
1: Mariah Carey - We Belong Together
2: Gwen Stefani - Hollaback Girl
3: Mario - Let Me Love You
4: Kelly Clarkson - Since U Been Gone
5: Ciara feat Missy Elliott - 1, 2 Step
2: Gwen Stefani - Hollaback Girl
3: Mario - Let Me Love You
4: Kelly Clarkson - Since U Been Gone
5: Ciara feat Missy Elliott - 1, 2 Step