Purpose: To establish a consensus on the complexity of 16 fundamental movement skills (FMS). Initially, complexity was defined as how difficult it would be to teach FMS to children and for the children to learn them. Method: The study was conducted using a modified Delphi method and a mobile application called Move Improve® to showcase video demonstrations of 16 FMS. Six experts discussed and rated the complexity of each FMS using a 5-point Likert scale until a 75% consensus was obtained during three rounds. Result: Dribble was rated as the most complex (average five) and run as the least (average one). The highest percentage of consensus at 100% was obtained for dribble, overhead throw, run, and skip during Round 3. Conclusion: Eye--hand or eye--foot coordination, laterality, and the environment were deemed as the most influential factors when rating the complexity of FMS.