Metro transit has good social and environmental benefits but cannot cover every corner of a city. Ridesourcing is being integrated with metros to provide first- and last-mile connections in many cities. Understanding the spatiotemporal characteristics of this integrated use is crucial for building more sustainable and cooperative multimodal urban mobility systems. However, integrated use has not been investigated comprehensively, owing to a lack of observed data. To fill this gap, a three-level structure was used to identify access- and egress-integrated ridesourcing trips based on 2 months of observed data from Shanghai metropolis, China. Afterward, the travel patterns of integrated trips were analyzed in temporal (weekdays and weekends) and spatial (urban and suburban areas) dimensions. Finally, the spatially heterogeneous effect of determinants on integrated use was evaluated via geographically weighted regression. The results indicated that more than 60% of integrated trips are concentrated in suburbs to serve first- and last-mile connections. The duration and distance of integrated trips in suburbs significantly exceed those in urban areas. Further examination indicated that determinants such as the transfer distance, metro ridership, and the distance to the city center are positively correlated with integrated use. The effects of these determinants on integrated use vary among stations. These findings can provide theoretical guidance for the coordinated development of emerging shared mobility services and traditional public transit modes.