| ITF - W75 Vero Beach | 01/23 20:05 | 25 | [248] Sofia Costoulas v Sachia Vickery [137] | 6-2,3-6,2-6 | |
| ITF - W35 Naples | 01/18 14:50 | 26 | [248] Sofia Costoulas v Vivian Wolff [399] | 6-4,3-6,1-6 | |
| ITF - W35 Naples | 01/17 17:10 | 25 | [248] Sofia Costoulas v Victoria Osuigwe [441] | 3-6,6-2,6-2 | |
| ITF - W25 Limassol | 12/03 09:00 | 29 | [255] Silvia Ambrosio v Sofia Costoulas [296] | 1-6,3-6 | |
| ITF - W25 Limassol | 12/02 08:00 | 28 | [296] Sofia Costoulas v Anastasia Zakharova [192] | 7-6,7-5 | |
| ITF - W25 Limassol | 12/01 08:00 | 27 | [296] Sofia Costoulas v Polina Iatcenko [358] | 7-5,7-5 | |
| ITF - W25 Limassol | 11/30 08:00 | 26 | [296] Sofia Costoulas v Hanne Vandewinkel [343] | 7-5,6-1 | |
| ITF - W25 Limassol | 11/29 08:00 | 25 | Sofia Costoulas v Angelina Wirges | 3-6,7-6,6-0 | |
| ITF - W25 Limassol | 11/26 09:00 | 29 | [330] Hanne Vandewinkel v Sofia Costoulas [291] | 6-2,4-6,6-4 | |
| ITF - W25 Limassol | 11/25 08:00 | 28 | [291] Sofia Costoulas v Anastasia Zakharova [192] | 6-2,7-5 | |
| ITF - W25 Limassol | 11/24 12:10 | 27 | Sofia Costoulas v Rebecca Munk Mortensen | 6-3,6-2 | |
| ITF - W25 Limassol | 11/23 08:00 | 26 | [291] Sofia Costoulas v Polina Iatcenko [356] | 6-4,6-0 | |
| ITF - W25 Limassol | 11/22 08:00 | 25 | [291] Sofia Costoulas v Weronika Falkowska [333] | 6-3,6-2 | |
| ITF - W40 Pétange | 11/17 16:00 | 27 | [101] Oceane Dodin v Sofia Costoulas [297] | 6-2,7-5 | |
| ITF - W40 Pétange | 11/16 08:50 | 26 | Sofia Costoulas v Veronika Podrez | 6-3,3-6,6-1 | |
| ITF - W40 Pétange | 11/15 12:55 | 25 | [267] Antonia Ruzic v Sofia Costoulas [297] | 4-6,7-6,1-6 | |
| ITF - W60 Nantes | 10/30 16:05 | 25 | [297] Sofia Costoulas v Natalija Stevanovic [185] | 2-6,7-6,4-6 | |
| ITF - W80 Poitiers | 10/26 12:20 | 26 | [111] Anna-Lena Friedsam v Sofia Costoulas [296] | 6-3,6-2 | |
| ITF - W80 Poitiers | 10/24 08:30 | 25 | Marine Szostak v Sofia Costoulas | 1-6,7-6,2-6 | |
| ITF - W60 Hamburgo | 10/17 09:10 | 25 | Alevtina Ibragimova v Sofia Costoulas | 2-6,6-4,6-4 | |
| ITF - W40 Quinta do Lago | 10/11 09:00 | 25 | [131] Olivia Gadecki v Sofia Costoulas [281] | 7-6,6-1 | |
| ITF - W25 Santarém | 09/27 13:15 | 25 | Laura Pigossi v Sofia Costoulas | Cancelled | |
| ITF - W25 Santarém | 09/27 09:00 | 25 | Alina Charaeva v Sofia Costoulas | 6-2,3-6,6-4 | |
| ITF - W25 Ceuta | 09/23 12:05 | 28 | [291] Sofia Costoulas v Aliona Falei [340] | 6-3,4-6,0-6 | |
| ITF - W25 Ceuta | 09/22 09:30 | 27 | Kira Pavlova v Sofia Costoulas | 5-7,3-6 | |
| ITF - W25 Ceuta | 09/21 08:00 | 26 | Anastasiia Grechkina v Sofia Costoulas | 4-6,2-6 | |
| ITF - W25 Ceuta | 09/19 13:30 | 25 | Arlinda Rushiti v Sofia Costoulas | 4-6,6-1,2-6 | |
| ITF - W25 Leiria | 09/14 10:00 | 26 | [288] Sofia Costoulas v Eva Guerrero Alvarez [434] | 4-6,6-3,3-6 | |
| ITF - W25 Leiria | 09/13 13:15 | 25 | Sofia Costoulas v Ranah Akua Stoiber | 6-3,6-0 | |
| ITF - W25 Verbier | 08/23 08:55 | 25 | [299] Sofia Costoulas v Berta Bonardi [419] | 7-5,5-7,3-6 |
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.