Abstract Background Early mobilisation of critically ill adults has been proven effective and is safe and feasible for critically ill children. However, barriers and perceived benefits of paediatric intensive care unit (PICU) staff involvement in mobilising critically ill children are largely unknown. Aim To explore the barriers and perceived benefits regarding early mobilisation of critically ill children as perceived by PICU staff. Study design A cross‐sectional survey study among staff from seven PICUs in the Netherlands has been carried out. Results Two hundred and fifteen of the 641 health care professionals (33.5%) who were invited to complete a questionnaire responded, of whom 159 (75%) were nurses, 40 (19%) physicians, and 14 (6%) physical therapists. Respondents considered early mobilisation potentially beneficial to shorten the duration of mechanical ventilation (86%), improve wake/sleep rhythm (86%) and shorten the length of stay in the PICU (85%). However, staff were reluctant to mobilise patients on extracorporeal membrane oxygenation (ECMO) (63%), and patients with traumatic brain injury (49%). Perceived barriers to early mobilisation were hemodynamic instability (78%), risk of dislocation of lines/tubes (74%), and level of sedation (62%). In total, 40.3% of PICU nurses stated that physical therapists provided enough support in their PICU, but 84.6% of the physical therapists believed support was sufficient. Conclusion Participating PICU staff considered early mobilisation as potentially beneficial in improving patient outcomes, although barriers were noted in certain patient groups. Relevance to clinical practice We identified barriers to early mobilisation which should be addressed in implementation research projects in order to make early mobilisation in critically ill children work.