Abstract Knee flexion contracture is a clinically important complication that can be observed after trauma, after knee surgery, or as a result of osteoarthritis. When it is left untreated, knee shearing forces increase not only in the affected joint but also in the contralateral knee, leading to mechanical overload in both limbs. Conservative management is a first‐line treatment option for extension deficits, but when it fails, surgical treatment is necessary. Open as well as arthroscopic techniques focus mainly on an anterior arthrolysis and a posterior capsular release. Until now, posterior capsulotomy involved either a medial posterior capsular release or medial and lateral posterior capsular releases. Our aim is to present the technique of arthroscopic complete posterior capsulotomy for knee flexion contractures. Technique Video video See video under supplementary data.