Ferencváros On 15 July 2021, Zachariassen signed a contract with Hungarian side
Ferencváros. On 5 May 2023, he won the
2022–23 Nemzeti Bajnokság I with
Ferencváros, after
Kecskemét lost 1–0 to
Honvéd at the
Bozsik Aréna on the 30th matchday. On 6 August 2023, he scored his first goal in the
2023–24 Nemzeti Bajnokság I season against
Fehérvár FC at the
Sóstói Stadion. He said in an interview with
Nemzeti Sport, that Ferencváros should beat
FK Čukarički in the first match day of the
2023–24 UEFA Europa Conference League. In an interview with Nemzeti Sport, he said that Ferencváros should not be afraid of Kecskemét, finished second in the
2022–23 Nemzeti Bajnokság I, ahead of the match at
Széktói Stadion against Kecskemét in the
2023–24 Nemzeti Bajnokság I. Finally, his fear was warranted since Kecskemét beat Ferencváros 2–1 on 5 November 2023. In an interview with Nemzeti Sport, he said that Ferencváros must beat Cukaricki if they want advance to the knockout stage. On 30 November 2023, he scored the equalizer against
FK Čukarički on the fifth match day of the
2023–24 UEFA Europa Conference League match. The match, finally, was won by Ferecváros 2–1 thanks to a late goal by
Aleksandar Pešić. On the last match day of the 2023–24 UEFA Europa Conference League, Zachariassen scored a goal against
ACF Fiorentina. The match ended with a 1–1 draw which meant that Ferencváros finished second in their group and qualified for the knockout stage. On 3 April 2024, he scored twice in a Magyar Kupa match against
Diósgyőri VTK at the
Diósgyőri Stadion in the
2023–24 Magyar Kupa season. On 20 April 2024, the
Ferencváros–
Kisvárda tie ended with a goalless draw at the
Groupama Aréna on the 29th match day of the
2023–24 Nemzeti Bajnokság I season which meant that Ferencváros won their 35th championship. On 15 May 2024, Ferencváros were defeated by Paks 2–0 in the
2024 Magyar Kupa Final at the
Puskás Aréna. On 7 November 2024, he scored the second goal in a 4-0 victory over
FC Dynamo Kyiv on the fourth match day of the
2024–25 UEFA Europa League league phase. Zachariassen won the
2024–25 Nemzeti Bajnokság I season with Ferencváros after beating
Győr 2–1 at the
ETO Park on the last match day on 24 May 2025. ==International career==