Stadium: Court 1 Round: 54 Ground: Synthetic outdoor
| ITF W60 Montreux | 2019/09/02 08:25 | Andreea Ghitescu v Mariia Kostiuk | 6-1,6-1 |
| ITF W60 Concord | 2019/08/12 20:50 | Sophia Whittle v Mariia Kostiuk | 6-1,6-1 |
| ITF W60 Concord | 2019/08/12 16:59 | Theresa Papikian v Mariia Kostiuk | 3-6,5-7 |
| ITF W60 Concord | 2019/08/12 16:20 | Theresa Papikian v Mariia Kostiuk | 3-6,5-7 |
| ITF W60 Landisville | 2019/08/05 18:45 | Ayaka Okuno v Mariia Kostiuk | 6-2,6-2 |
| ITF W60 Ashland | 2019/07/22 16:35 | Mariia Kostiuk v Rhiann Newborn | 3-6,1-6 |
| ITF W25 Osprey | 2019/04/22 14:30 | Mariia Kostiuk v Chanelle Van Nguyen | 5-7,2-6 |