| 1. Jornada | 14.08.2020 | NK Opatija | - | Hajduk Split II | 2:1 | ||||
| 2. Jornada | 22.08.2020 | NK Sesvete | - | NK Opatija | 0:1 |  |
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| 4. Jornada | 12.09.2020 | NK Rudeš | - | NK Opatija | 1:2 | ||||
| 6. Jornada | 19.09.2020 | NK Dubrava | - | NK Opatija | 1:4 | ||||
| 3. Jornada | 23.09.2020 | NK Opatija | - | NK Solin | 1:1 | |
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| 7. Jornada | 27.09.2020 | NK Opatija | - | HNK Orijent Rijeka | 1:1 | |
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| 9. Jornada | 03.10.2020 | NK Opatija | - | NK Osijek II | 1:1 | ||||
| 11. Jornada | 14.11.2020 | NK Opatija | - | NK Dugopolje | 2:1 | ||||
| 14. Jornada | 21.11.2020 | NK Kustošija | - | NK Opatija | 2:1 | ||||
| 13. Jornada | 25.11.2020 | NK Opatija | - | NK Inter Zaprešić | 3:2 | ||||
| 16. Jornada | 05.12.2020 | NK Opatija | - | Dinamo Zagreb II | 2:1 | |
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| 17. Jornada | 13.12.2020 | NK BSK Bijelo Brdo | - | NK Opatija | 1:1 | ||||
| 19. Jornada | 20.02.2021 | NK Opatija | - | NK Sesvete | 1:0 | ||||
| 22. Jornada | 14.03.2021 | HNK Cibalia | - | NK Opatija | 2:0 | ||||
| 23. Jornada | 20.03.2021 | NK Opatija | - | NK Dubrava | 2:1 | ||||
| 28. Jornada | 24.04.2021 | NK Dugopolje | - | NK Opatija | 0:0 | |
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| 32. Jornada | 16.05.2021 | NK Croatia Zmijavci | - | NK Opatija | 1:3 | ||||
| 34. Jornada | 29.05.2021 | NK Opatija | - | NK BSK Bijelo Brdo | 2:2 |
Croacia