The present invention relates to a downhole tubing cutter tool for submerging into a casing in a wellbore and separating an upper part of the casing from a lower part of the casing by cutting the casing from within, the tool extending in a longitudinal direction, comprising a tool housing having a first and a second housing part, a cutting arm which is pivotably connected with the first housing part and has a cutting edge in a first end, said arm being movable between a retracted position and a projected position in relation to the tool housing, an arm activation assembly for moving the cutting arm between the retracted position and the projected position, and a rotatable shaft arranged in the second housing part and connected with the first housing part for rotating the cutting arm.