Jalmari Helander was originally going to direct a comedic sci-fi film "Jerry and Ms Universe" in Canada. When it was postponed due to the COVID-19 pandemic, he quickly wrote Sisu (2022) in the fall of 2021. The film's budget is around $6 million.
The actors by and large insisted on doing their own stunts.
The exteriors are shot in Finnish Lapland, mainly near the villages of Nuorgam and Kaamanen in the Utsjoki municipality.
The film's shooting title was "The Immortal".
Jack Doolan had to clear with his agent whether the offer to appear in the film was for real as he felt it was such a bat-shit crazy script that it couldn't be genuine.