| 24 jul 2026 | Habig, Bryan 2077 | Den Hartog, Marijn 2209 | 0-1 | A21 Apertura Inglesa: King's English Variation, Kramnik-Shirov Counterattack | Dutch Open 2026 - Dutch Open | 76 | Ver |
| 23 jul 2026 | Den Hartog, Marijn 2209 | Harshavardhan G B 2508 | 0-1 | C77 Apertura Española (Ruy López): Morphy Defense, Anderssen Variation | Dutch Open 2026 - Dutch Open | 35 | Ver |
| 22 jul 2026 | Lu, Yunong Elias 2112 | Den Hartog, Marijn 2209 | 0-1 | B31 Defensa Siciliana: Nyezhmetdinov-Rossolimo Attack, Fianchetto Variation | Dutch Open 2026 - Dutch Open | 27 | Ver |
| 21 jul 2026 | Den Hartog, Marijn 2209 | Peyrer, Konstantin 2496 | 0-1 | A05 Ataque Indio de Rey: Symmetrical Defense | Dutch Open 2026 - Dutch Open | 48 | Ver |
| 19 jul 2026 | Schoorl, Rob 2284 | Den Hartog, Marijn 2209 | ½-½ | A37 Apertura Inglesa: Symmetrical Variation, Three Knights, Fianchetto Variation | Amsterdam Chess Festival 2026 - Groep A | 10 | Ver |
| 18 jul 2026 | Den Hartog, Marijn 2209 | Dovgaliuk, Oleksandr 2305 | 1-0 | E05 Apertura Catalana: Open Defense, Classical Line | Amsterdam Chess Festival 2026 - Groep A | 83 | Ver |
| 17 jul 2026 | Den Hartog, Marijn 2209 | Brienen, Jacob 2090 | 1-0 | A46 Defensa India: Knights Variation | Amsterdam Chess Festival 2026 - Groep A | 34 | Ver |
| 15 jul 2026 | De Boer, Eelke 2406 | Den Hartog, Marijn 2209 | 1-0 | C54 Apertura Italiana: Classical Variation, Giuoco Pianissimo | Amsterdam Chess Festival 2026 - Groep A | 23 | Ver |
| 14 jul 2026 | Den Hartog, Marijn 2209 | Bosboom, Manuel 2328 | 1-0 | A40 Apertura de Peón de Dama: Modern Defense | Amsterdam Chess Festival 2026 - Groep A | 44 | Ver |
| 10 jul 2026 | Albers, Sasa 2365 | Den Hartog, Marijn 2209 | ½-½ | A10 Apertura Inglesa | Amsterdam Chess Festival 2026 - Groep A | 34 | Ver |
| 24 may 2026 | Simenon, Jozef 2288 | Den Hartog, Marijn 2209 | 1-0 | A00 Apertura Polaca | Qualification Dutch Championship 2026 | 43 | Ver |
| 24 may 2026 | Den Hartog, Marijn 2209 | Kamphuis, Jasper 2134 | 0-1 | C26 Apertura Vienesa: Mieses Variation | Qualification Dutch Championship 2026 | 35 | Ver |
| 24 may 2026 | Terlouw, Wouter 2259 | Den Hartog, Marijn 2209 | 1-0 | D31 Gambito de Dama rehusado: Janowski Variation | Qualification Dutch Championship 2026 | 55 | Ver |
| 24 may 2026 | Den Hartog, Marijn 2209 | Van der Werf, Mark 2384 | 0-1 | A00 Mieses Opening | Qualification Dutch Championship 2026 | 50 | Ver |
| 24 may 2026 | Slagboom, Leandro 2334 | Den Hartog, Marijn 2209 | 0-1 | C10 Defensa Francesa: Rubinstein Variation, Kasparov Attack | Qualification Dutch Championship 2026 | 63 | Ver |
| 24 may 2026 | Den Hartog, Marijn 2209 | Ootes, Lars 2363 | 0-1 | B00 Defensa Pirc | Qualification Dutch Championship 2026 | 34 | Ver |
| 23 may 2026 | De Boer, Eelke 2406 | Den Hartog, Marijn 2209 | 0-1 | C02 Defensa Francesa: Advance Variation, Euwe Variation | Qualification Dutch Championship 2026 | 57 | Ver |
| 23 may 2026 | Den Hartog, Marijn 2209 | Jellema, Pieter 2193 | 1-0 | B10 Defensa Caro-Kann: Endgame Variation | Qualification Dutch Championship 2026 | 47 | Ver |
| 23 may 2026 | Grooten, Tommy 2356 | Den Hartog, Marijn 2209 | 0-1 | D31 Gambito de Dama rehusado: Janowski Variation | Qualification Dutch Championship 2026 | 24 | Ver |
| 23 may 2026 | Aravindhan, Achyuth 2213 | Den Hartog, Marijn 2209 | ½-½ | B12 Defensa Caro-Kann | Qualification Dutch Championship 2026 | 47 | Ver |