| ITF W25 Corroios-Seixal | 07/12 10:00 | 25 | Aliona Falei v Sofia Costoulas | 6-4,2-6,6-3 | |
| ITF W25 Tainan | 06/20 03:40 | 25 | [285] Sofia Costoulas v Yi Tsen Cho [414] | 3-6,4-6 | |
| ITF W25 Tainan | 06/15 04:35 | 26 | [476] Ayano Shimizu v Sofia Costoulas [281] | 6-4,3-6,7-6 | |
| ITF W25 Tainan | 06/14 04:10 | 25 | Samantha Imbo Nloga v Sofia Costoulas | 2-6,1-6 | |
| ITF W25 Troisdorf | 05/31 12:20 | 25 | Sofia Costoulas v Gina M Dittmann | 3-6,6-3,5-7 | |
| ITF W60 Grado | 05/24 11:25 | 26 | [325] Sofia Costoulas v Hailey Baptiste [244] | 3-6,2-6 | |
| ITF W60 Grado | 05/23 07:30 | 25 | [338] Anna Siskova v Sofia Costoulas [325] | 0-6,1-6 | |
| ITF W25 Feld am See | 05/20 10:05 | 29 | Lara Salden v Sofia Costoulas | 3-6,1-6 | |
| ITF W25 Feld am See | 05/19 09:00 | 28 | [326] Sofia Costoulas v Elvina Kalieva [243] | 6-2,6-3 | |
| ITF W25 Feld am See | 05/18 08:00 | 27 | [345] Maja Chwalinska v Sofia Costoulas [326] | 4-6,4-6 | |
| ITF W25 Feld am See | 05/17 11:00 | 26 | [367] Kayla Cross v Sofia Costoulas [326] | 7-5,5-7,3-6 | |
| ITF W25 Feld am See | 05/17 07:30 | 25 | Arabella Koller v Sofia Costoulas | 6-4,4-6,1-6 | |
| ITF W25 Osijek | 04/27 10:40 | 26 | [334] Sofia Costoulas v Tena Lukas [233] | 4-6,1-6 | |
| ITF W25 Osijek | 04/26 09:30 | 25 | [334] Sofia Costoulas v Julia Avdeeva [465] | 2-6,6-3,7-6 | |
| ITF W60 Bellinzona | 04/17 12:35 | 24 | [342] Andrea Lazaro Garcia v Sofia Costoulas [358] | 7-5,6-3 | |
| ITF W25 Santa Margherita | 04/15 11:50 | 28 | [411] Andreea Prisacariu v Sofia Costoulas [360] | 6-1,1-6,6-2 | |
| ITF W25 Santa Margherita | 04/14 11:10 | 27 | Sofia Costoulas v Federica Bilardo | 6-4,6-4 | |
| ITF W25 Santa Margherita | 04/13 08:30 | 26 | [301] Matilde Paoletti v Sofia Costoulas [360] | 1-6,3-6 | |
| ITF W25 Santa Margherita | 04/11 14:15 | 25 | [360] Sofia Costoulas v Ikumi Yamazaki [426] | 7-6,6-2 | |
| ITF W60 Pretoria | 03/16 08:00 | 26 | [192] Ipek Oz v Sofia Costoulas [347] | 7-6,6-1 | |
| ITF W60 Pretoria | 03/14 09:25 | 25 | [347] Sofia Costoulas v Lucie Nguyen Tan [378] | 6-3,6-1 | |
| ITF W25 Pretoria | 03/11 08:00 | 28 | [347] Sofia Costoulas v Emina Bektas [325] | 3-6,6-4,6-7 | |
| ITF W25 Pretoria | 03/10 08:00 | 27 | [338] Jenny Duerst v Sofia Costoulas [347] | 4-6,3-6 | |
| ITF W25 Pretoria | 03/09 09:40 | 26 | [366] Alice Tubello v Sofia Costoulas [347] | 2-6,2-6 | |
| ITF W25 Pretoria | 03/08 09:50 | 25 | [347] Sofia Costoulas v Selena Janicijevic [210] | 7-6,7-5 | |
| ITF W25 Santo Domingo | 02/24 14:00 | 27 | [417] Stacey Fung v Sofia Costoulas [361] | 2-6,7-6,6-4 | |
| ITF W25 Santo Domingo | 02/23 16:35 | 26 | [361] Sofia Costoulas v Sada Nahimana [263] | 6-2,6-0 | |
| ITF W25 Santo Domingo | 02/22 13:30 | 25 | Sofia Costoulas v Eliessa Vanlangendonck | 6-3,0-6,6-3 | |
| ITF W25 Santo Domingo | 02/14 14:55 | 24 | Sofia Costoulas v Clara Vlasselaer | 6-4,3-6,6-7 | |
| ITF W40 Mexico City | 02/07 15:30 | 25 | [364] Sofia Costoulas v Despina Papamichail [154] | 6-7,2-6 |
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.