| UTR Pro Tennis Series Barcelona - Dames | 2021/06/09 12:00 | Mariia Kostiuk v Valentyna Ivakhnenko | 1-6,1-5 |
| ITF W25 - Madrid | 2021/06/06 09:00 | Mariia Kostiuk v Maria Garcia Cid | 1-6,1-6 |
| ITF W25 - Calvi | 2021/04/11 12:10 | Rebecca Amerio v Mariia Kostiuk | 6-4,6-1 |
| ITF W25 Manacor | 2021/03/09 09:00 | Olga Parres Azcoitia v Mariia Kostiuk | 6-2,6-1 |
| ITF - W25 Selva Gardena | 2020/12/13 13:20 | Mariia Kostiuk v Verena Hofer | 3-6,3-6 |
| ITF W15 - LPD Gran Canaria | 2020/11/23 10:15 | Mariia Kostiuk v Rebeca Pereira | 1-6,0-6 |
| ITF W15 - LPD Gran Canaria | 2020/11/22 09:30 | Mariia Kostiuk v Maria Fernanda Morales | 6-3,6-1 |
| ITF Women Castellon | 2020/11/01 10:30 | Mariia Kostiuk v Maria B Bandera | 3-6,1-6 |
| UTR Pro Tennis Series Barcelona - Dames | 2021/06/09 11:00 | Sarah Tatu v Romy Kolzer | 0-6,3-6 |
| UTR Pro Tennis Series Barcelona - Dames | 2021/06/07 11:00 | Ares Teixido Garcia v Romy Kolzer | 2-6,6-6 |
| UTR Pro Tennis Series - Kopenhagen - Dames | 2021/05/29 10:00 | Romy Kolzer v Johanne C Svendsen | 5-7,3-5 |