In 2009 she directed her debut film Pure, an adaptation of one of her plays starring Alicia Vikander as Katarina.

Langseth's 2013 comedy-drama Hotell debuted at the 2013 Toronto International Film Festival in the Contemporary World Cinema program.

Her most recent film is titled Euphoria, featuring regular collaborator Vikander, along with Eva Green and Charlotte Rampling.

It describes a conflict between two sisters, Ines (Alicia Vikander) and Emilie (Eva Green), who then travel through Europe towards a mystery destination.

In 2019, Netflix announced that Langseth would be the creator for its second Swedish-language TV series, Love & Anarchy.