| Apr 19, 2026 | Thorsteinsson | 1–0 | Osiecki | Round 1: Thorsteinsson, Thorsteinn - Osiecki, Stanislaw | East Indian Defense | |
| Jul 11, 2024 | Osiecki | ½–½ | Mertens | wst50 | Sicilian Defense: Alapin Variation, Smith-Morra Declined | |
| Jul 10, 2024 | Osiecki | ½–½ | Slabek | wst50 | Scandinavian Defense | |
| Jul 9, 2024 | Zeidler | 1–0 | Osiecki | wst50 | French Defense: Exchange Variation | |
| Jul 7, 2024 | Osiecki | 1–0 | Marinello | wstcc2024o50 | Caro-Kann Defense: Advance Variation, Botvinnik-Carls Defense | |
| Jul 6, 2024 | Osiecki | 0–1 | Dahl | wstcc2024o50 | Sicilian Defense: Alapin Variation, Smith-Morra Declined | |
| Jul 5, 2024 | Crocker | 1–0 | Osiecki | wstcc2024o50 | King's Indian Defense: Fianchetto Variation, Long Variation | |
| Jul 4, 2024 | Osiecki | ½–½ | Westphal | wstcc2024o50 | St. George Defense | |
| Jul 3, 2024 | Schuster | 1–0 | Osiecki | wstcc2024o50 | King's Indian Defense: Averbakh Variation, Main Line | |
| Jul 2, 2024 | Kaspi | 1–0 | Osiecki | wstcc2024o50 | Old Indian Defense | |
| May 15, 2024 | Osiecki | 0–1 | Nikcevic | European Senior Team Chess Championship 2024 - Section 50 + | Ruy Lopez: Classical Variation | |
| May 8, 2024 | Frick | ½–½ | Osiecki | European Senior Team Chess Championship 2024 - Section 50 + | French Defense: Winawer Variation, Classical Variation | |
| Jul 20, 2023 | Osiecki | ½–½ | Hill | European Senior Team Chess Championship 2023 50+ | French Defense: Advance Variation, Paulsen Attack | |
| Jul 19, 2023 | Mrva | 1–0 | Osiecki | European Senior Team Chess Championship 2023 50+ | King's Indian Defense: Normal Variation, Rare Defenses | |
| Jul 18, 2023 | Osiecki | 0–1 | Rewitz | European Senior Team Chess Championship 2023 50+ | Caro-Kann Defense: Advance Variation | |
| Jul 17, 2023 | Buckley | 1–0 | Osiecki | European Senior Team Chess Championship 2023 50+ | French Defense: Advance Variation, Main Line | |
| Jul 16, 2023 | Osiecki | 0–1 | Hebden | European Senior Team Chess Championship 2023 50+ | Ruy Lopez: Exchange Variation, King's Bishop Variation | |
| Jul 15, 2023 | Burnett | ½–½ | Osiecki | European Senior Team Chess Championship 2023 50+ | King's Indian Defense: Semi-Averbakh System | |
| Jul 14, 2023 | Baliuniene | 0–1 | Osiecki | European Senior Team Chess Championship 2023 50+ | King's Indian Defense: Orthodox Variation, Positional Defense | |
| Jul 13, 2023 | Osiecki | 1–0 | Kowalczuk | European Senior Team Chess Championship 2023 50+ | Petrov's Defense: Modern Attack, Center Variation | |
| Jul 12, 2023 | Lalic | 1–0 | Osiecki | European Senior Team Chess Championship 2023 50+ | French Defense: Advance Variation, Paulsen Attack | |
| Jun 18, 2023 | Osiecki | 1–0 | Stepien | Mistrzostwa Polski Seniorow 2023 | Sicilian Defense: Alapin Variation | |
| Jun 17, 2023 | Osiecki | 1–0 | Bobrowski | Mistrzostwa Polski Seniorow 2023 | Modern Defense: Bishop Attack | |
| Jun 16, 2023 | Leszner | 1–0 | Osiecki | Mistrzostwa Polski Seniorow 2023 | French Defense: King's Indian Attack | |
| Jun 15, 2023 | Osiecki | ½–½ | Karczynski | Mistrzostwa Polski Seniorow 2023 | Alekhine Defense: Modern Variation, Main Line | |
| Jun 15, 2023 | Poniewierski | 0–1 | Osiecki | Mistrzostwa Polski Seniorow 2023 | English Opening: Anglo-Indian Defense, King's Indian Formation | |
| Jun 12, 2023 | Czarnolewski | ½–½ | Osiecki | Mistrzostwa Polski Senior�w 2023 | French Defense: Advance Variation, Main Line | |
| — | Osiecki | 1–0 | Wierzejski | rubinsteinE | Scandinavian Defense | |
| — | Osiecki | 1–0 | Chmielewski | rubinsteinE | Caro-Kann Defense: Advance Variation | |
| — | Osiecki | 0–1 | Klimaszewski | rubinsteinE | Sicilian Defense: Alapin Variation | |
| — | Osiecki | 1–0 | Pyka | rubinsteinE | Scandinavian Defense | |
| — | Osiecki | ½–½ | Betkowski | rubinsteinE | French Defense: Advance Variation, Paulsen Attack | |
| — | Szydelko | 1–0 | Osiecki | rubinsteinE | King's Indian Defense: Makogonov Variation | |
| — | Stadnicki | 0–1 | Osiecki | rubinsteinE | King's Indian Defense: Orthodox Variation, Positional Defense | |
| — | Fikus | 0–1 | Osiecki | rubinsteinE | King's Indian Defense: Normal Variation, Standard Development | |
| — | Kowalczuk | ½–½ | Osiecki | rubinsteinE | French Defense: Chigorin Variation | |
