The purpose of this systematic review was to determine the outcome of interphalangeal (IP) joint motion in children undergoing open surgical release, splinting, and passive exercising therapy for the treatment of paediatric trigger thumb. We conducted an online literature search of seven major databases. Only studies with a mean follow-up of at least 12 months were considered for inclusion. Seventeen retrospective studies and one prospective study met all the inclusion criteria. They reported on the results of surgery (634 children, 759 thumbs), splinting (115 children, 138 thumbs), and passive exercising (89 children, 108 thumbs). The mean follow-up periods were 59 (surgery), 23 (splinting), and 76 months (exercising), respectively. Full IP joint motion without residual triggering was achieved in 95% of all children undergoing surgery, in 67% of children treated with continuous splinting, and 55% after passive exercising. Based on the low level of evidence available, it seems that open surgery resulted in more reliable and rapid outcomes compared with nonoperative treatment.