These are the Billboard Hot 100 number-one hits of 1981. The longest running number-one single of 1981 is "Physical" by Olivia Newton-John which stayed at the top of the chart for six weeks in 1981 and then for four additional weeks in 1982, with a total of ten weeks at number-one.
| Issue Date | Song | Artist(s) | Reference |
|---|---|---|---|
| January 3 | "(Just Like) Starting Over" | John Lennon | |
| January 10 | |||
| January 17 | |||
| January 24 | |||
| January 31 | "The Tide Is High" | Blondie | |
| February 7 | "Celebration" | Kool & the Gang | |
| February 14 | |||
| February 21 | "9 to 5" | Dolly Parton | |
| February 28 | "I Love a Rainy Night" | Eddie Rabbitt | |
| March 7 | |||
| March 14 | "9 to 5" | Dolly Parton | |
| March 21 | "Keep on Loving You" | REO Speedwagon | |
| March 28 | "Rapture" | Blondie | |
| April 4 | |||
| April 11 | "Kiss on My List" | Daryl Hall and John Oates | |
| April 18 | |||
| April 25 | |||
| May 2 | "Morning Train (Nine to Five)" | Sheena Easton | |
| May 9 | |||
| May 16 | "Bette Davis Eyes" | Kim Carnes | |
| May 23 | |||
| May 30 | |||
| June 6 | |||
| June 13 | |||
| June 20 | "Stars on 45 Medley" | Stars on 45 | |
| June 27 | "Bette Davis Eyes" | Kim Carnes | |
| July 4 | |||
| July 11 | |||
| July 18 | |||
| July 25 | "The One That You Love" | Air Supply | |
| August 1 | "Jessie's Girl" | Rick Springfield | |
| August 8 | |||
| August 15 | "Endless Love" | Diana Ross and Lionel Richie | |
| August 22 | |||
| August 29 | |||
| September 5 | |||
| September 12 | |||
| September 19 | |||
| September 26 | |||
| October 3 | |||
| October 10 | |||
| October 17 | "Arthur's Theme (Best That You Can Do)" | Christopher Cross | |
| October 24 | |||
| October 31 | |||
| November 7 | "Private Eyes" | Daryl Hall and John Oates | |
| November 14 | |||
| November 21 | "Physical" | Olivia Newton-John | |
| November 28 | |||
| December 5 | |||
| December 12 | |||
| December 19 | |||
| December 26 |
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