Urbanisation is a major driver of habitat fragmentation and pollinator decline. Although urban green spaces are increasingly recognized as important refuges for pollinator conservation, most studies have focused on habitat types such as parks, gardens, allotments, and urban meadows. In contrast, grasslands running along rivers remain poorly studied despite being widespread features of European cities and potentially functioning as ecological corridors with less interruption across fragmented urban landscapes. We investigated wild bee and hoverfly communities along an urban riverside grassland corridor of the Arno River (Florence). Pollinators and flowering vegetation were surveyed along eight permanent transects during two consecutive years (2024–2025). We assessed pollinator diversity and community composition in relation to local floral resources, landscape composition, habitat configuration, microclimatic temperatures, and plant–pollinator interactions associated with spontaneous flowering vegetation. The study area supported unexpectedly high pollinator diversity relative to its limited spatial extent, especially for wild bees. Beta-diversity analyses revealed that community differences along the corridor were mainly driven by species turnover rather than nestedness, indicating that the corridor functions as a heterogeneous mosaic of local assemblages of pollinator communities. Consistently, local habitat conditions emerged as the main drivers of pollinator communities. Flowering plant richness and floral cover positively influenced both abundance and richness of wild bees and hoverflies, while warmer local conditions additionally promoted wild bee abundance. In contrast, the percentage of artificial surfaces showed no detectable effects, whereas habitat configuration, calculated as an index of contiguity, positively influenced hoverfly richness. Plant–pollinator interaction analyses highlighted the importance of a limited set of spontaneous flowering species in sustaining pollinator communities. Our results suggest that urban riparian grasslands are overlooked but valuable habitats for pollinator conservation and may enhance ecological connectivity within urban landscapes, emphasizing the potential of local floral management to create more biodiverse and pollinator-friendly cities.