As a transitional space that connects urban and rural elements, the mobility behavior of peri-urban residents is key to understanding the mechanisms of urban–rural interaction and the logic of spatial organization. A systematic investigation of peri-urban residents’ mobility behavior patterns has important theoretical and practical significance for promoting integrated urban–rural development. Taking Lanzhou as a case study, this research integrates LBS trajectory data with POI data to construct a three-dimensional indicator system comprising mobility generation intensity, spatial agglomeration degree, and average dwell time, and employs the K-means clustering method to systematically depict the spatiotemporal behavioral characteristics and patterns of peri-urban residents’ movements toward the main urban area.The results show that, in the temporal dimension, mobility behavior exhibits regular differentiation and functional complementarity characterized by a weekday commuting-oriented pattern and a non-workday leisure-oriented multi-peak pattern. In the spatial dimension, the mobility pattern demonstrates strong axial corridorization, forming a stable structure of multi-source convergence, corridor movement along axial routes, and node-based agglomeration. In addition, cluster analysis identifies three typical behavioral patterns—leisure consumers, urban commuters, and polycentric active users—revealing significant intra-group differentiation among peri-urban residents shaped by varying activity needs and spatiotemporal preferences.From the perspective of integrating a special urban form with an urban–rural transitional space, this study deepens the understanding of human–land interaction in ribbon-shaped cities and provides a scientific basis for optimizing regional transportation networks, allocating public service facilities, and formulating differentiated peri-urban development policies.