| Welsh Int. | 11/26 13:40 | - | Leon Seiwald v Marius Reboul L'Alexandre | L | 0-2 | |
| Hungarian Int. | 10/31 12:50 | - |
Karan R Rajarajan
v
Leon Seiwald |
L | 2-0 | |
| Hungarian Int. | 10/31 09:10 | - | Adam Konczol v Leon Seiwald | W | 0-2 | |
| Hungarian Int. | 10/30 13:30 | - | Luca Zhou v Leon Seiwald | W | 0-2 | |
| Hungarian Int. | 10/30 08:20 | - | Carl Claesson v Leon Seiwald | W | 0-2 | |
| Slovenia Open Quals | 05/16 08:00 | - | Bima Al Ayman Modjo v Leon Seiwald | L | 2-0 | |
| Slovenia Open Quals | 05/15 12:20 | - | Leon Seiwald v Aditya Patil | W | 2-0 | |
| Slovak Open Qual | 04/17 14:35 | - | Tauri Kilk v Leon Seiwald | L | 2-0 | |
| Slovak Open Qual | 04/17 07:45 | - |
Leon Seiwald v
James Robertson
|
W | 2-0 | |
| Austrian Open Qual | 05/27 09:40 | - | Jan Janostik v Leon Seiwald | - | Retired | |
| Euro Mixed Team Champs | 12/10 17:30 | - | Milan Ludik v Leon Seiwald | W | 0-2 | |
| SaarLorLux Open | 10/27 09:00 | 6 | Leon Seiwald v Kim Bruun | L | 0-2 | |
| Slovak Open | 02/27 15:30 | - |
Jan Louda
v
Leon Seiwald |
L | 2-0 | |
| Austrian Open Qual | 02/19 12:15 | - | Leon Seiwald v Rahul Yadav Chittaboina | L | 1-2 | |
| European Team Championships | 02/13 18:00 | - | Leon Seiwald v Joshua Magee | W | 2-1 | |
| European Team Championships | 02/12 19:00 | - | Leon Seiwald v Mateusz Dubowski | W | 2-1 | |
| Scottish Open Qual | 11/21 12:40 | - |
Christo Popov
v
Leon Seiwald |
L | 2-0 | |
| Scottish Open Qual | 11/21 10:00 | - | Leon Seiwald v Sam Parsons | W | 2-1 | |
| Irish Open Qual | 11/13 14:30 | - | Daniel Nikolov v Leon Seiwald | L | 2-0 | |
| Irish Open Qual | 11/13 11:05 | - | Leon Seiwald v Victor Pang | W | 2-0 | |
| Hungarian Int. Qual | 10/30 17:10 | - |
Leon Seiwald v
Tobias Kuenzi
|
L | 0-2 | |
| Polish Int. | 09/21 09:55 | 4 | Ivan Rusev v Leon Seiwald | L | 2-0 | |
| Polish Int. | 09/20 10:20 | 5 | Leon Seiwald v Joonas Korhonen | W | 2-1 | |
| Belgian Int. | 09/12 13:00 | 5 | Luis Enrique Penalver v Leon Seiwald | L | 2-1 | |
| Belgian Int. Qual | 09/11 08:10 | - | Leon Seiwald v Fikri Ihsandi Hadmadi | - | Walkover | |
| Kharkiv Int. Qual | 09/04 11:30 | - | Leon Seiwald v Gergo Pytel | L | 1-2 | |
| Belarus Int. | 08/30 10:40 | - | Raul Must v Leon Seiwald | L | 2-1 | |
| Slovenia Int. Qual | 05/15 08:30 | - |
Leon Seiwald v
Rahul Bharadwaj B.M
|
L | 0-2 | |
| Swiss Open WD Qual | 02/21 09:10 | - | Bobby Setiabudi v Leon Seiwald | L | 2-0 | |
| Swiss Open WD Qual | 12/13 13:45 | 1 | Mikkel Enghoj v Leon Seiwald | W | 0-1 |