| Apr 28, 2026 | Littlewood | ½–½ | Thorsteinsson | Round 9: Littlewood, Paul E - Thorsteinsson, Thorsteinn | Queen's Gambit Declined: Exchange Variation, Positional Variation | |
| Apr 26, 2026 | Petran | 1–0 | Thorsteinsson | Round 7: Petran, Peter - Thorsteinsson, Thorsteinn | Hungarian Opening | |
| Apr 23, 2026 | Thorsteinsson | ½–½ | Aulin-Jansson | Round 5: Thorsteinsson, Thorsteinn - Aulin-Jansson, Joran | Zukertort Opening | |
| Apr 22, 2026 | Baarslag | ½–½ | Thorsteinsson | Round 4: Baarslag, Ed - Thorsteinsson, Thorsteinn | Sicilian Defense: Hyperaccelerated Dragon | |
| Apr 20, 2026 | Thorsteinsson | ½–½ | Granat | Round 2: Thorsteinsson, Thorsteinn - Granat, Russell G | Slav Defense: Breyer Variation | |
| Apr 19, 2026 | Thorsteinsson | 1–0 | Osiecki | Round 1: Thorsteinsson, Thorsteinn - Osiecki, Stanislaw | East Indian Defense | |
| Mar 8, 2026 | Einarsson | ½–½ | Thorsteinsson | Icelandic team chess championship premier league | Catalan Opening | |
| Mar 7, 2026 | Thorsteinsson | ½–½ | Kjartansson | Icelandic team chess championship premier league | English Opening: Symmetrical Variation, Ultra-Symmetrical Variation | |
| Nov 15, 2025 | Thorsteinsson | 1–0 | Runarsson | Icelandic team chess championship premier league | King's Indian Defense: Steiner Attack | |
| Oct 5, 2025 | Wahlbom | ½–½ | Thorsteinsson | European individual senior chess championship 2025 - Open 65+, Rabac, Croatia | Ruy Lopez: Closed, Chigorin Defense | |
| Oct 4, 2025 | Stoinev | ½–½ | Thorsteinsson | European individual senior chess championship 2025 - Open 65+, Rabac, Croatia | Sicilian Defense: Nyezhmetdinov-Rossolimo Attack, Fianchetto Variation | |
| Oct 3, 2025 | Thorsteinsson | ½–½ | Knaak | European individual senior chess championship 2025 - Open 65+, Rabac, Croatia | Zukertort Opening | |
| Oct 1, 2025 | Thorsteinsson | 1–0 | Alquist | European individual senior chess championship 2025 - Open 65+, Rabac, Croatia | Benoni Defense: King's Pawn Line, with Bg5 | |
| Sep 29, 2025 | Thorsteinsson | 1–0 | Suhogerlla | European individual senior chess championship 2025 - Open 65+, Rabac, Croatia | Queen's Gambit Declined: Three Knights Variation | |
| Sep 28, 2025 | Hammar | 0–1 | Thorsteinsson | European individual senior chess championship 2025 - Open 65+, Rabac, Croatia | Sicilian Defense: Dragon Variation, Classical Variation | |
| Sep 24, 2025 | Bilobrk | 1–0 | Thorsteinsson | European individual senior chess championship 2025 - Open 65+, Rabac, Croatia | Queen's Indian Defense: Kasparov-Petrosian Variation, Hedgehog Variation | |
| Sep 24, 2025 | Boulard | ½–½ | Thorsteinsson | European individual senior chess championship 2025 - Open 65+, Rabac, Croatia | Sicilian Defense: Dragon Variation | |
| Sep 12, 2025 | Thorsteinsson | ½–½ | Birkisson | Haustmot TR 2025 | Slav Defense: Quiet Variation, Schallopp Defense | |
| Sep 10, 2025 | Birkisson | 1–0 | Thorsteinsson | Haustmot TR 2025 | Sicilian Defense: Dragon Variation, Yugoslav Attack, Early Deviations | |
| Sep 3, 2025 | Thorsteinsson | ½–½ | Ptacnikova | Haustmot TR 2025 | Nimzo-Indian Defense: Normal Variation | |
| Sep 3, 2025 | Johannesson | ½–½ | Thorsteinsson | Haustmot TR 2025 | Queen's Gambit Declined: Exchange Variation, Sämisch Variation | |
| Sep 3, 2025 | Thorsteinsson | 0–1 | Ragnarsson | Haustmot TR 2025 | Queen's Pawn Game: Symmetrical Variation | |
| Sep 3, 2025 | Stefansson | 1–0 | Thorsteinsson | Haustmot TR 2025 | Sicilian Defense: Dragon Variation | |
| Sep 3, 2025 | Thorsteinsson | 1–0 | Omarsson | Haustmot TR 2025 | East Indian Defense | |
| Sep 3, 2025 | Thorsteinsson | ½–½ | Omarsson | Haustmot TR 2025 | King's Indian Defense: Kramer Variation | |
| Sep 3, 2025 | Thorfinnsson | ½–½ | Thorsteinsson | Haustmot TR 2025 | Torre Attack: Classical Defense, Nimzowitsch Variation | |
| Aug 29, 2021 | Thorsteinsson | 1–0 | Kueng | European Individual Chess Championship 2021 - Reykjavik Open | English Opening: Anglo-Indian Defense | |
| Aug 28, 2021 | Blohberger | 1–0 | Thorsteinsson | European Individual Chess Championship 2021 - Reykjavik Open | French Defense: Tarrasch Variation, Closed Variation | |
| Aug 27, 2021 | Thorsteinsson | 1–0 | Tummasarson | European Individual Chess Championship 2021 - Reykjavik Open | Grünfeld Defense: Three Knights Variation, Petrosian System | |
| Aug 26, 2021 | Durarbayli | 1–0 | Thorsteinsson | European Individual Chess Championship 2021 - Reykjavik Open | Sicilian Defense: Accelerated Dragon, Maróczy Bind | |
| — | Thorsteinsson | ½–½ | Arngrimsson | Icelandic Team Championship | English Opening: Caro-Kann Defensive System | |
| — | Thorsteinsson | ½–½ | Kulaots | Icelandic Team Championship | Indian Defense: Knights Variation | |
| — | Hansen | ½–½ | Thorsteinsson | Icelandic Team Championship | Sicilian Defense: Dragon Variation | |
