| ITF Women Saguenay | 10/23 14:00 | 25 | Elitsa Kostova v Jada Bui | 4-6,3-6 | |
| WTA Lucembursko | 10/14 11:50 | 46 | [208] Elitsa Kostova v Arantxa Rus [112] | 2-6,3-6 | |
| WTA Lucembursko | 10/13 19:35 | 45 | Indy De Vroome v Elitsa Kostova | 3-6,2-6 | |
| ITF Women Santa Margherita | 10/02 13:50 | 25 | [324] Reka-Luca Jani v Elitsa Kostova [211] | 7-5,4-6,6-1 | |
| ITF Women Santa Margherita | 09/28 12:00 | 27 | [197] Elitsa Kostova v Ludmilla Samsonova [185] | 3-6,4-6 | |
| ITF Women Santa Margherita | 09/27 12:00 | 26 | [197] Elitsa Kostova v Irene B. Escorihuela [405] | 6-0,5-7,6-2 | |
| ITF Women Santa Margherita | 09/25 17:15 | 25 | [197] Elitsa Kostova v Jule Niemeier [463] | 7-5,6-1 | |
| ITF Women Saint Malo | 09/18 10:20 | 25 | [195] Elitsa Kostova v Cagla Buyukakcay [246] | 6-7,4-6 | |
| ITF Women Biarritz | 09/12 13:25 | 25 | [92] Carina Witthoeft v Elitsa Kostova [179] | 6-4,7-6 | |
| ITF Women Zagreb | 09/06 16:50 | 26 | Elitsa Kostova v Tena Lukas | 6-1,2-6,3-6 | |
| ITF Women Zagreb | 09/05 16:15 | 25 | [179] Elitsa Kostova v Agnes Bukta [492] | 6-3,6-4 | |
| ITF Women Budapest | 08/28 09:00 | 25 | Raluca Georgiana Serban v Elitsa Kostova | 6-2,7-5 | |
| US Open - ženy | 08/21 16:15 | 44 | [176] Elitsa Kostova v Fiona Ferro [130] | 1-6,7-5,4-6 | |
| ITF Women Prague | 07/27 10:40 | 27 | [177] Elitsa Kostova v Richel Hogenkamp [166] | 6-7,7-6,2-6 | |
| ITF Women Prague | 07/26 13:10 | 26 | [177] Elitsa Kostova v Lucrezia Stefanini [458] | 6-2,6-4 | |
| ITF Women Prague | 07/25 09:30 | 25 | Elitsa Kostova v Katarina Zavatska | 6-2,4-6,6-4 | |
| WTA Gstaad | 07/18 10:30 | 26 | [104] Marketa Vondrousova v Elitsa Kostova [186] | 6-4,6-4 | |
| WTA Gstaad | 07/17 08:30 | 25 | [186] Elitsa Kostova v Anna Kalinskaya [132] | 6-4,0-6,6-2 | |
| ITF Women Versmold | 07/12 09:10 | 25 | [322] Laura Siegemund v Elitsa Kostova [183] | 6-2,6-4 | |
| Wimbledon Women Qual | 06/26 10:00 | 44 | [158] Jamie Loeb v Elitsa Kostova [178] | 1-6,7-5,6-1 | |
| ITF Women Manchester | 06/13 10:00 | 25 | [99] Viktorija Golubic v Elitsa Kostova [186] | 6-3,6-4 | |
| ITF Women Stare Splavy | 06/09 12:30 | 28 | [176] Elitsa Kostova v Rebecca Sramkova [343] | 7-5,4-6,4-6 | |
| ITF Women Stare Splavy | 06/08 11:15 | 27 | Elitsa Kostova v Ani Mijacika | 6-2,2-6,6-4 | |
| ITF Women Stare Splavy | 06/07 09:30 | 26 | [176] Elitsa Kostova v Anna Bondar [415] | 6-3,3-6,6-1 | |
| ITF Women Stare Splavy | 06/06 09:50 | 25 | [176] Elitsa Kostova v Martina Colmegna [472] | 6-4,6-7,7-6 | |
| French Open Women Qual | 05/23 08:00 | 44 | [174] Elitsa Kostova v Tamara Korpatsch [145] | 4-6,6-2,3-6 | |
| WTA Anning | 05/03 04:00 | 27 | [39] Shuai Peng v Elitsa Kostova [189] | 6-1,6-0 | |
| WTA Anning | 05/02 03:00 | 26 | [189] Elitsa Kostova v Dalila Jakupovic [124] | 7-6,0-6,6-1 | |
| WTA Anning | 05/01 03:00 | 25 | [189] Elitsa Kostova v Jacqueline Cako [236] | 6-4,6-1 | |
| WTA Istanbul Qual | 04/23 13:20 | - | [123] Arantxa Rus v Elitsa Kostova [190] | 6-2,6-0 |