| ITF M15 Doha | 2019/03/05 12:00 | Michiel de Krom v Guy Den Heijer | 5-7,6-3,9-11 |
| ITF M15 Almada | 2021/07/07 08:30 | Michiel de Krom v Duarte Vale | 3-6,3-6 |
| ITF M25 The Hague | 2021/06/28 08:45 | Carlos Lopez Montagud v Michiel de Krom | 6-1,6-3 |
| ITF M25 The Hague | 2021/06/27 08:00 | Tom Clavel v Michiel de Krom | 3-6,5-7 |
| ITF M25 Alkmaar | 2021/06/21 17:30 | Marvin Moeller v Michiel de Krom | 2-6,6-4,10-3 |
| ITF M25 Alkmaar | 2021/06/20 17:00 | Constantin Bittoun Kouzmine v Michiel de Krom | 3-6,3-6 |
| ITF M15 Valldoreix | 2021/05/09 14:00 | Michiel de Krom v Federico Iannaccone | 3-6,2-6 |
| ITF M15 Majadahonda | 2021/05/05 06:55 | Martin Cuevas v Michiel de Krom | 7-5,6-3 |
| ITF M25 Reus | 2021/04/13 10:00 | Yan Bondarevskiy v Michiel de Krom | 6-3,6-3 |
| UTR Pro Tennis Series Mulheim | 2021/07/30 13:30 | Guy Den Heijer v Alexander Hoogmartens | 6-2,3-6,4-6 |
| UTR Pro Tennis Series Mulheim | 2021/07/29 13:30 | Mark Wallner v Guy Den Heijer | 2-6,3-6 |
| UTR Pro Tennis Series Mulheim | 2021/07/29 07:00 | Matthew Thomson v Guy Den Heijer | 1-6,3-6 |
| UTR Pro Tennis Series Mulheim | 2021/07/27 09:30 | Billy Harris v Guy Den Heijer | 3-6,2-6 |
| UTR Pro Tennis Series Mulheim | 2021/07/26 11:00 | Guy Den Heijer v Tim Sandkaulen | 7-5,6-3 |
| ITF M25 Marburg | 2021/07/07 10:50 | Aleksandre Metreveli v Guy Den Heijer | 6-3,1-6,6-2 |
| ITF M25 Marburg | 2021/07/06 12:25 | Guy Den Heijer v Florian Broska | 6-3,7-6 |
| ITF M25 Marburg | 2021/07/05 08:00 | Guy Den Heijer v Maximilian Homberg | 6-7,6-2,10-8 |