Background <p>The use of diapers among older adults is increasing in aging societies. However, the optimal method of wearing them remains unknown. We aimed to explore procedural variations in leg-through motion during diaper wearing in older adults.</p> Methods <p>A multicenter cross-sectional study was conducted in 19 facilities in Japan. Individuals aged 65–99 years in nursing homes/adult daycare facilities and able to maintain a sitting posture in a chair were recruited via convenience sampling between March 2024 and January 2025. Leg-through motion during diaper wearing was recorded with the participants seated in a chair. The motion patterns were visually classified according to predetermined criteria. The classification of the observed motion patterns was subjected to a simple descriptive analysis. The inter-rater agreement of the classifications between the two assessors was determined using Cohen’s kappa coefficient.</p> Results <p>Among 149 older adults (mean [standard deviation] age: 87.0 [7.2] years), the motions “keep the foot off the floor and use both hands” and “keep feet on the floor and use both hands” collectively accounted for 65.7% of the initial leg motions. For the subsequent leg, three motions—“keep the foot off the floor and use contralateral hand,” “keep the foot off the floor and use ipsilateral hand,” and “keep the foot off the floor and use both hands”—accounted for a total of 59.1%. Furthermore, the leg-through motion patterns varied according to the participants’ usual means of mobility. The inter-rater agreement was good for the initial leg (kappa = 0.72) and subsequent leg (0.80).</p> Conclusions <p>We classified the motion patterns of older adults during diaper wearing. Our results provide fundamental insights into appropriate care and rehabilitation interventions. Furthermore, these findings inform further hypothesis-driven research on diaper-wearing kinematics and support the development of effective strategies to enhance independence diaper use in older adults.</p>