| ITF W40 Ciudad de México | 02/03 19:40 | 28 | [128] Yue Yuan v Sofia Costoulas [406] | 6-4,6-1 | |
| ITF W40 Ciudad de México | 02/02 18:30 | 27 | [406] Sofia Costoulas v Lina Glushko [260] | 6-3,6-3 | |
| ITF W40 Ciudad de México | 02/01 17:20 | 26 | [406] Sofia Costoulas v Estelle Cascino [141] | 6-2,6-1 | |
| ITF W40 Ciudad de México | 01/31 19:35 | 25 | [210] Suzan Lamens v Sofia Costoulas [406] | 5-7,0-6 | |
| ITF W25 Buenos Aires | 01/18 14:15 | 25 | Chantal Sauvant v Sofia Costoulas | 6-7,6-4,6-1 | |
| ITF W25 Buenos Aires | 01/14 13:00 | 28 | [441] Sofia Costoulas v Nuria Brancaccio [265] | 2-6,3-6 | |
| ITF W25 Buenos Aires | 01/13 14:00 | 27 | [441] Sofia Costoulas v Carlota M Cirez [315] | 6-2,6-0 | |
| ITF W25 Buenos Aires | 01/12 17:50 | 26 | [390] Yuliana Lizarazo v Sofia Costoulas [441] | 6-4,1-6,2-6 | |
| ITF W25 Buenos Aires | 01/11 14:35 | 25 | Natalia Siedliska v Sofia Costoulas | 6-4,5-7,2-6 | |
| ITF W25 Petange | 11/25 11:00 | 27 | [433] Sofia Costoulas v Magali Kempen [241] | 4-6,3-6 | |
| ITF W25 Petange | 11/24 10:00 | 26 | Daria Lopatetska v Sofia Costoulas | 7-5,5-7,2-6 | |
| ITF W25 Petange | 11/23 15:00 | 25 | [433] Sofia Costoulas v Audrey Albie [318] | 6-7,7-6,6-2 | |
| ITF W25 Sharm El Sheikh | 11/16 07:30 | 25 | [440] Giulia G-Monticone v Sofia Costoulas [430] | 6-3,6-3 | |
| ITF W25 Loughborough | 10/26 10:30 | 26 | Martyna Kubka v Sofia Costoulas | Walkover | |
| ITF W25 Loughborough | 10/25 15:00 | 25 | [449] Sofia Costoulas v Yuriko Lily Miyazaki [215] | 6-2,3-6,6-3 | |
| ITF W25 Loughborough | 10/24 10:40 | 54 | Sofia Costoulas v Holly Hutchinson | 6-3,7-6 | |
| ITF W25 Hua Hin | 10/12 05:20 | 25 | Sofia Costoulas v Erika Sema | 3-6,5-7 | |
| ITF W25 Hua Hin | 10/08 03:55 | 28 | [496] Sofia Costoulas v Xiaodi You [304] | 6-4,1-6,2-6 | |
| ITF W25 Hua Hin | 10/07 07:30 | 27 | [457] Yexin Ma v Sofia Costoulas [496] | 2-6,6-3,5-7 | |
| ITF W25 Hua Hin | 10/06 07:05 | 26 | Sofia Costoulas v Anchisa Chanta | 4-6,6-4,6-0 | |
| ITF W25 Hua Hin | 10/05 05:50 | 25 | Clara Vlasselaer v Sofia Costoulas | 3-6,3-6 | |
| ITF W25 Vigo | 08/25 11:00 | 26 | Xiaodi You v Sofia Costoulas | 6-0,6-4 | |
| ITF W25 Vigo | 08/24 08:55 | 25 | Lucia L Domingo v Sofia Costoulas | 2-6,0-6 | |
| ITF W25 Foxhills | 08/02 09:00 | 25 | Sofia Costoulas v Fang Ying Xun | 6-2,3-6,4-6 | |
| ITF W25 Gurugram | 06/30 04:00 | 26 | Sofia Costoulas v Ankita Raina | Retired | |
| ITF W25 Gurugram | 06/29 09:30 | 25 | Sofia Costoulas v Akanksha D Nitture | 6-1,6-2 | |
| ITF W25 Gurugram | 06/26 04:30 | 29 | Sofia Costoulas v Karman Kaur Thandi | 4-6,6-2,1-6 | |
| ITF W25 Gurugram | 06/25 04:30 | 28 | Sofia Costoulas v Saki Imamura | 6-2,6-4 | |
| ITF W25 Gurugram | 06/24 04:30 | 27 | Diana Marcinkevica v Sofia Costoulas | 4-6,4-6 | |
| ITF W25 Gurugram | 06/23 06:30 | 26 | Sofia Costoulas v Ekaterina Yashina | 6-7,6-1,7-5 |
Sofia Costoulas (born 2 April 2005) is a Belgian tennis player.
Costoulas has a Greek–Congolese father and a Belgian mother.
Costoulas has a career-high singles ranking by the Women's Tennis Association (WTA) of 248 and a best doubles ranking of 229.
On the ITF Junior Circuit, she had a career-high combined ranking of No. 2, achieved on 18 April 2022. She lost the girls' singles final of the 2022 Australian Open to Petra Marčinko. She had already reached the Wimbledon junior doubles final in 2021.