Aim: To investigate the relationship between Self-Determination Theory’s motivational regulations and fundament movement skills (FMS) in primary school children. Quality of physical activity (PA) motivation has been found to be an important correlate and a potential determinant of PA. However, there are few that have investigated the quality of PA motivation’s relationship with determinants and correlates of PA, such as fundamental movement skills (FMS). There is an increasing recognition of the relationship between FMS and PA in childhood, with studies beginning to show a causal relationship. Thus, this study investigates the relationship between children’s quality of PA motivation and their FMS proficiency. The motivation and FMS of 865 children (47.7% female, 10.9 ± 1.16 years) was collected. The TGMD-3 (Ulrich, 2017) was implemented to evaluate FMS. Meanwhile, quality of motivation was measured using the BREQ which was adapted for children (Sebire et al., 2013). A hierarchical multiple regression was conducted to assess the capacity of four measures (intrinsic motivation, identified, introjected and external regulations) on FMS proficiency, with separate male and female analysis. The four measures explained 8.9% of the variance in FMS for males (R2 = .089, p < .001) and 5.5% for females (R2 = .055, p < .001). For males, three measures were statistically significant (p < .05): identified (β = .21), external (β = -.14), and introjected (β = .13) regulation. Meanwhile, for females only external regulation (β = -.21) made a significant contribution to FMS. The results of the current research are congruent with previous SDT research, demonstrating how motivation quality influences FMS proficiency. It is no surprise that FMS proficiency and intrinsic motivation do not have a significant relationship; perhaps developing FMS proficiency requires individuals to place value on the skills and to recognise the importance of FMS in terms of facilitating their participation and success in PA. This study provides evidence for the need to promote autonomous motivation and prevent controlling motivation when designing, testing and implementing FMS interventions.