| 15 may 2026 | Li, Yunqi 2130 | Mueller, Konstantin 2058 | 1-0 | D28 Gambito de Dama aceptado: Classical Defense, Alekhine System | DEM U12 2026 | 36 | Ver |
| 23 abr 2026 | Ivanovic, Leonid 2184 | Mueller, Konstantin 2058 | ½-½ | A16 Apertura Inglesa: Anglo-Indian Defense, Anglo-Grünfeld Variation | European School Chess Championship 2026 - Open U11 | 31 | Ver |
| 29 mar 2026 | Strehse, Nelson 2239 | Mueller, Konstantin 2037 | 1-0 | A16 Apertura Inglesa: Anglo-Indian Defense, Anglo-Grünfeld Variation | Runde 4: Strehse, Nelson - Mueller, Konstantin | 49 | Ver |
| 30 dic 2025 | Mueller, Konstantin 2075 | Weihrauch, Jakob 2249 | 0-1 | B22 Defensa Siciliana: Alapin Variation | DVM U20 2025 | 70 | Ver |
| 29 dic 2025 | Sabirov, Rafael 2173 | Mueller, Konstantin 2075 | ½-½ | B22 Defensa Siciliana: Alapin Variation, Stoltz Attack | DVM U20 2025 | 43 | Ver |
| 29 dic 2025 | Mueller, Konstantin 2075 | Riechenberg, Sebastian 2174 | ½-½ | D37 Gambito de Dama rehusado: Three Knights Variation | DVM U20 2025 | 28 | Ver |
| 27 dic 2025 | Danninger, Hugo Kian 2151 | Mueller, Konstantin 2075 | ½-½ | A48 East Indian Defense | DVM U20 2025 | 28 | Ver |
| 20 dic 2025 | Mueller, Konstantin 2180 | Asici, Poyraz Efe 2001 | 0-1 | E19 Defensa India de Dama: Classical Variation, Traditional Variation, Main Line | FIDE World U9-U17 Rapid & Blitz Chess Championships | Blitz (Boards 1-100) | 56 | Ver |
| 20 dic 2025 | Zhauynbay, Alimzhan 2065 | Mueller, Konstantin 2180 | 1-0 | B97 Defensa Siciliana: Najdorf Variation, Poisoned Pawn Accepted | FIDE World U9-U17 Rapid & Blitz Chess Championships | Blitz (Boards 1-100) | 47 | Ver |
| 27 oct 2025 | Protopopescu, Luca 2043 | Mueller, Konstantin 2040 | 1-0 | B33 Defensa Siciliana: Lasker-Pelikan Variation, Sveshnikov Variation | European Youth Chess Championship 2025 | U10 | 97 | Ver |
| 5 oct 2025 | Mueller, Konstantin 2052 | Voigt, Anastasia 2076 | 1-0 | B15 Defensa Caro-Kann: Tartakower Variation | Deutsche Ländermeisterschaft 2025 | 42 | Ver |