UNLABELLED: Primary malignant bone tumors are significant health concerns in children. These tumors, often accompanied by pain, fatigue, and reduced physical function, can lead to the development of kinesiophobia, a fear of movement that can further complicate rehabilitation. Although factors associated with kinesiophobia have been examined in various adult cancer populations, there is limited research on kinesiophobia and its predictors in children with bone tumors. This study aims to investigate the factors contributing to kinesiophobia in pediatric bone tumor patients. This prospective cross-sectional study was conducted in children with primary malignant bone tumors aged 8-17 years who actively on treatment. The Tampa Scale for Kinesiophobia (TSK) was used to assess fear of movement. Other assessments included the numerical rating scale (NRS) for pain, the PedsQL™ Multidimensional Fatigue Scale for fatigue, the Children Depression Rating Scale-Revised (CDRS-R) for depression, manual muscle testing, and the TUG Test for functionality. Logistic regression was performed to identify predictors of kinesiophobia, while chi-square tests examined the relationship between muscle strength and kinesiophobia levels. One hundred children with bone tumors an average age of 11.83 years participated in the study. The logistic regression model indicated that surgery status, pain levels, and fatigue were significant predictors of kinesiophobia, with an R CONCLUSION: This study highlights the multifactorial nature of kinesiophobia in children with malignant bone tumors, emphasizing the roles of surgical status, pain, and psychological factors. Integrating biopsychosocial assessments and approaches into routine care may be important to reduce kinesiophobia, improve rehabilitation outcomes, and increase overall well-being. WHAT IS KNOWN: • Kinesiophobia has been studied in adult cancer populations and has been associated with decreased physical activity and poorer rehabilitation outcomes. WHAT IS NEW: • This study demonstrates that surgery status, pain levels, and fatigue are significant predictors of kinesiophobia in children with malignant bone tumors and highlights that, in addition to various cancer-related symptoms, kinesiophobia can also be present in this population.