| Champ: |  Rafael Nadal |
| Runner: | Stefanos Tsitsipas |
| Score: | 6–2, 6–1 |
| Type: | singles doubles |
| Draw: | 48 (6 / 5) |
| Seeds: | 16 |
See main article: 2018 Barcelona Open Banco Sabadell.
Two-time defending champion Rafael Nadal[1] defeated Stefanos Tsitsipas in the final, 6–2, 6–1 to win the singles tennis title at the 2018 Barcelona Open. Nadal did not drop a set en route to his record-extending eleventh Barcelona Open title and his 20th ATP 500 title overall, equaling Roger Federer's record. He retained the world No. 1 singles ranking with the win. It was Tsitsipas' first ATP Tour final.
All seeds received a bye into the second round.