Diede de Groot defeated the defending champion Yui Kamiji in a rematch of the previous year's final, 6–2, 6–3 to win the women's singles wheelchair tennis title at the 2018 US Open. It was her first US Open singles title, and was her second step towards a non-calendar-year Grand Slam.
Seeds
Diede de Groot (champion)
Yui Kamiji (final)
Draw
Key
- Q = Qualifier
- WC = Wild card
- LL = Lucky loser
- Alt = Alternate
- SE = Special exempt
- PR = Protected ranking
- ITF = ITF entry
- JE = Junior exempt
- w/o = Walkover
- r = Retired
- d = Defaulted
- SR = Special ranking
Bracket
| Quarterfinals | Semifinals | Final | ||||||||||||||||||
| 1 | Diede de Groot
| 6 | 6 | |||||||||||||||||
| Aniek van Koot
| 1 | 2 | ||||||||||||||||||
| 1 | Diede de Groot
| 6 | 6 | |||||||||||||||||
 Sabine Ellerbrock
| 0 | 3 | ||||||||||||||||||
| WC |  Dana Mathewson
| 1 | 2 | |||||||||||||||||
| Sabine Ellerbrock
| 6 | 6 | ||||||||||||||||||
| 1 | Diede de Groot
| 6 | 6 | |||||||||||||||||
| 2 | Yui Kamiji
| 2 | 3 | |||||||||||||||||
 Kgothatso Montjane
| 6 | 6 | ||||||||||||||||||
 Lucy Shuker
| 4 | 4 | ||||||||||||||||||
| Kgothatso Montjane
| 1 | 0 | ||||||||||||||||||
| 2 | Yui Kamiji
| 6 | 6 | |||||||||||||||||
| Marjolein Buis
| 0 | 0 | ||||||||||||||||||
| 2 | Yui Kamiji
| 6 | 6 | |||||||||||||||||