This is a list of songs which reached number one on the Billboard Mainstream Top 40 (or Pop Songs) chart in 2018.
During 2018, a total of 19 singles hit number-one on the charts.
| † | Indicates best-performing single of 2018[1] |
| Issue date | Song | Artist(s) | Ref. |
|---|---|---|---|
| January 3 | "Havana" | Camila Cabello featuring Young Thug | [2] |
| January 6 | [3] | ||
| January 13 | [4] | ||
| January 20 | "Perfect" | Ed Sheeran | [5] |
| January 27 | [6] | ||
| February 3 | "New Rules" † | Dua Lipa | [7] |
| February 10 | [8] | ||
| February 17 | [9] | ||
| February 24 | [10] | ||
| March 3 | "Perfect" | Ed Sheeran | [11] |
| March 10 | "Let You Down" | NF | [12] |
| March 17 | "Him &I" | G-Eazy and Halsey | [13] |
| March 24 | [14] | ||
| March 31 | "Finesse" | Bruno Mars featuring Cardi B | [15] |
| April 7 | "The Middle" | Zedd, Maren Morris and Grey | [16] |
| April 14 | [17] | ||
| April 21 | [18] | ||
| April 28 | [19] | ||
| May 5 | [20] | ||
| May 12 | "Never Be the Same" | Camila Cabello | [21] |
| May 19 | [22] | ||
| May 26 | [23] | ||
| June 2 | "The Middle" | Zedd, Maren Morris and Grey | [24] |
| June 9 | [25] | ||
| June 16 | "Psycho" | Post Malone featuring Ty Dolla Sign | [26] |
| June 23 | [27] | ||
| June 30 | [28] | ||
| July 7 | [29] | ||
| July 14 | "Mine" | Bazzi | [30] |
| July 21 | "No Tears Left to Cry" | Ariana Grande | [31] |
| July 28 | "Delicate" | Taylor Swift | [32] |
| August 4 | "Girls Like You" | Maroon 5 featuring Cardi B | [33] |
| August 11 | [34] | ||
| August 18 | [35] | ||
| August 25 | [36] | ||
| September 1 | [37] | ||
| September 8 | "Better Now" | Post Malone | [38] |
| September 15 | [39] | ||
| September 22 | "Love Lies" | Khalid and Normani | [40] |
| September 29 | [41] | ||
| October 6 | "Youngblood" | 5 Seconds of Summer | [42] |
| October 13 | [43] | ||
| October 20 | [44] | ||
| October 27 | [45] | ||
| November 3 | [46] | ||
| November 10 | "God Is a Woman" | Ariana Grande | [47] |
| November 17 | "Happier" | Marshmello and Bastille | [48] |
| November 24 | [49] | ||
| December 1 | [50] | ||
| December 8 | [51] | ||
| December 15 | "High Hopes" | Panic! at the Disco | [52] |
| December 22 | [53] | ||
| December 29 | [54] |
