In health care, work-related musculoskeletal disorders are largely attributed to patient-handling tasks. Reliable assessments of patient mobility are imperative to mitigate the musculoskeletal burden on healthcare providers. This study explores the reliability of MK5 Mobility Classes, a patient mobility classification system. Authentic video material was collected, which enabled many healthcare providers to evaluate patient mobility within a highly realistic practical environment. Inter-rater and intra-rater reliability were determined using the intraclass correlation coefficient (ICC). A total of 147 raters completed the MK5 assessment for 40 distinct practical cases. Additionally, 75 raters repeated the assessments. The high level of inter-rater reliability, ICC value of 0.82, demonstrates the consistent performance of MK5 in assessing patient mobility across diverse scenarios. Intra-rater reliability results showed moderate agreement, with an average ICC of 0.59. This study confirms the reliability of the MK5 Mobility Classes in assessing patient mobility in healthcare settings.