| European Championships | 04/10 17:00 | - | Viktor Axelsen v Kai Schaefer | L | 2-0 | |
| Spain Masters Qual | 03/26 09:45 | 4 | Yushi Tanaka v Kai Schaefer | L | 2-0 | |
| Polish Open | 03/23 15:00 | - | Kai Schaefer v Viktor Ording Kauffman | L | 1-2 | |
| Polish Open | 03/23 15:00 | - | Kai Schaefer v Victor Kauffmann | L | 1-2 | |
| Polish Open | 03/23 09:00 | - | Kalle Koljonen v Kai Schaefer | W | 0-2 | |
| Polish Open | 03/22 14:40 | - | Kai Schaefer v Markus Barth | W | 2-0 | |
| Orleans Masters Qual | 03/12 13:40 | - | Daniil Dubovenko v Kai Schaefer | L | 2-1 | |
| Orleans Masters Qual | 03/12 11:55 | 4 | Kai Schaefer v Danylo Bosniuk | W | 2-0 | |
| Portugal Int. | 03/09 17:20 | - | Matthias Kicklitz v Kai Schaefer | L | 2-0 | |
| Portugal Int. | 03/09 10:40 | - | Kai Schaefer v Rafael Gavois | W | 2-0 | |
| Portugal Int. | 03/08 10:40 | - | Kai Schaefer v Aria Dinata | W | 2-1 | |
| German Open Qual | 02/27 08:00 | 4 | S. Sankar Muthusamy Subramanian v Kai Schaefer | L | 2-0 | |
| European Team Championships | 02/16 09:00 | - | Jan Louda v Kai Schaefer | L | 2-1 | |
| Azerbaijan Int. | 02/10 06:40 | - | Daniil Dubovenko v Kai Schaefer | L | 2-1 | |
| Azerbaijan Int. | 02/09 09:40 | - | Kai Schaefer v Giovanni Toti | W | 2-1 | |
| Swedish Open | 01/19 14:00 | - | Kai Schaefer v Enogat Roy | L | 0-2 | |
| Swedish Open | 01/19 13:00 | - | Kai Schaefer v Gregoire Deschamp | W | 2-0 | |
| Irish Open | 11/17 10:40 | - | Pablo Abian v Kai Schaefer | L | 2-1 | |
| Irish Open | 11/16 16:00 | - | Kai Schaefer v Joakim Oldorff | W | 2-1 | |
| Irish Open | 11/16 11:00 | - | Kai Schaefer v Gustav Bjorkler | W | 2-1 | |
| Korea Masters | 11/09 06:25 | - | Kai Schaefer v Kento Momota | L | 0-2 | |
| Korea Masters | 11/08 10:20 | 5 | Kai Schaefer v Luis Enrique Penalver | W | 2-1 | |
| Hylo Open | 11/01 09:40 | 5 | Kai Schaefer v Toma Junior Popov | L | 0-2 | |
| Abu Dhabi Masters | 10/18 13:05 | 5 | Duc Phat Le v Kai Schaefer | L | 2-1 | |
| Abu Dhabi Masters | 10/18 06:00 | 6 | Aashinsa Herath v Kai Schaefer | W | 0-2 | |
| Dutch Open | 10/13 12:30 | - | Kai Schaefer v Karan Rajan Rajarajan | L | 1-2 | |
| Dutch Open | 10/12 10:20 | - | Kai Schaefer v Gregoire Deschamp | W | 2-1 | |
| Scottish Open | 10/06 14:40 | - | Collins Valentine Filimon v Kai Schaefer | L | 2-1 | |
| Scottish Open | 10/06 09:20 | - | Bernardo Atilano v Kai Schaefer | W | 0-2 | |
| Belgian Int. | 09/14 11:15 | - | Kai Schaefer v Louis Ducrot | L | 1-2 |
Kai Hendrik Schäfer (born 13 June 1993) is a German badminton player. He competed at the 2020 Tokyo Olympics.