Thomsen moved to Norwegian club Vålerenga in 2021, before returning to Denmark again, signing with SønderjyskE in January 2022.

[2] Thomsen made his debut for AaB in the Danish Superliga as a starter in a 1–2 loss against Midtjylland on 4 April 2012.

[11] He made his debut for the club on 15 July 2017 in a 1–1 league draw against his former team AaB, coming on as a substitute in the second half for Kasper Kusk.

[18][19] He made his debut for the club on 15 August in a 1–1 league draw away against Tromsø IL, replacing the suspended Christian Borchgrevink at right back.

[25] He made his full debut on 18 February, providing an assist to Stefan Gartenmann in a 3–2 home loss to AGF.

[26] The following week, he was sent off early in a 1–0 league loss to Brøndby after receiving his second yellow card due to a challenge on Carl Björk.

[35] Thomsen scored the only Danish goal in the 1–1 draw against Iceland which qualified Denmark U-21 for the 2015 UEFA European Under-21 Championship.

[36] He was selected for the squad for the tournament and played the entire match in the opening win against the Czech Republic.

Thomsen started his own menswear brand, Another Aspect, alongside childhood friends Anders Poulsen and Daniel Brøndt in 2019.