| Game |
| Result | Moves |
Year | Event/Locale | Opening |
| 26. J Ruiz vs D S Kostov |
| 0-1 | 21 | 2023 | TCh-SUI | B48 Sicilian, Taimanov Variation |
| 27. D S Kostov vs P Schlosser |
| ½-½ | 38 | 2024 | GRENKE Chess Open | A80 Dutch |
| 28. C Noe vs D S Kostov |
| 1-0 | 67 | 2024 | GRENKE Chess Open | D27 Queen's Gambit Accepted, Classical |
| 29. D S Kostov vs L Milov |
| ½-½ | 27 | 2024 | GRENKE Chess Open | A80 Dutch |
| 30. A Krstulovic vs D S Kostov |
| 0-1 | 59 | 2024 | GRENKE Chess Open | D05 Queen's Pawn Game |
| 31. S Kazantzoglou vs D S Kostov |
| ½-½ | 71 | 2024 | Basel Christmas Open | A07 King's Indian Attack |
| 32. D S Kostov vs T Villiers |
| 1-0 | 60 | 2024 | Basel Christmas Open | D45 Queen's Gambit Declined Semi-Slav |
| 33. M Cornette vs D S Kostov |
| 1-0 | 45 | 2024 | Basel Christmas Open | D02 Queen's Pawn Game |
| 34. D S Kostov vs A Ciolek |
| 1-0 | 30 | 2024 | Basel Christmas Open | D35 Queen's Gambit Declined |
| 35. D S Kostov vs S Citak |
| 1-0 | 47 | 2024 | Basel Christmas Open | E49 Nimzo-Indian, 4.e3, Botvinnik System |
| 36. A Shchekachev vs D S Kostov |
| 1-0 | 40 | 2024 | Basel Christmas Open | A07 King's Indian Attack |
| 37. D S Kostov vs V Ivic |
| 0-1 | 47 | 2025 | OGD Rapid | E71 King's Indian, Makagonov System (5.h3) |
| 38. L Vrolijk vs D S Kostov |
| 0-1 | 31 | 2025 | OGD Rapid | A06 Reti Opening |
| 39. D S Kostov vs M Bosboom |
| 1-0 | 43 | 2025 | OGD Rapid | E90 King's Indian |
| 40. A Dgebuadze vs D S Kostov |
| ½-½ | 7 | 2025 | OGD Rapid | D26 Queen's Gambit Accepted |
| 41. D S Kostov vs J Cuenca Jimenez |
| 1-0 | 91 | 2025 | Menorca Open | D35 Queen's Gambit Declined |
| 42. Z Agmanov vs D S Kostov |
| ½-½ | 47 | 2025 | Menorca Open | C02 French, Advance |
| 43. D S Kostov vs V Matviishen |
| ½-½ | 32 | 2025 | Menorca Open | D35 Queen's Gambit Declined |
| 44. A Woodward vs D S Kostov |
| ½-½ | 54 | 2025 | Menorca Open | D20 Queen's Gambit Accepted |
| 45. D S Kostov vs S Iermito |
| ½-½ | 40 | 2025 | Menorca Open | D25 Queen's Gambit Accepted |
| 46. D S Kostov vs J Baum |
| 0-1 | 71 | 2025 | Menorca Open | E49 Nimzo-Indian, 4.e3, Botvinnik System |
| 47. D S Kostov vs G Darshan |
| 1-0 | 42 | 2025 | 3rd Munich Whitsun Open A | D35 Queen's Gambit Declined |
| 48. F Sieber vs D S Kostov |
| 0-1 | 35 | 2025 | 3rd Munich Whitsun Open A | B48 Sicilian, Taimanov Variation |
| 49. D S Kostov vs E Safarli |
| 0-1 | 79 | 2025 | 3rd Munich Whitsun Open A | A45 Queen's Pawn Game |
| 50. V S Nandish vs D S Kostov |
| ½-½ | 51 | 2025 | 3rd Munich Whitsun Open A | D27 Queen's Gambit Accepted, Classical |
Kibitzing
