The ‘last mile’ is not only a powerful metaphor of contemporary life, but also the tangible site of a challenge, whether for governments wanting to reach their citizens or companies wanting to reach their customers. In urban Africa this challenge is compounded by the fragmented material condition of cities. As a result, a growing number of tech companies have been compelled by the possibility of creating digital platforms that address the unique logistical configurations of African cities, often enrolling informal systems such as motorcycle taxis to address spatial and economic fragmentation. Through the perspective of three Nairobi-based startups that incorporate motorcycle taxis into their last-mile platforms, this article illustrates how processes of ‘algorithmic suturing’ knit together the loose ends of splintered urban networks thanks to platform business models that visualize the last mile as a site of optimization. In parallel with common understandings of suturing within African infrastructure debates which foreground makeshift practices of the urban poor, this article argues that algorithmic suturing is a speculative endeavour through which urban fractures are made legible as sites of value. By stitching together city fragments, these platforms envision large data-driven urban economies which interface with informal mobility networks and the shifting urban demographic of the lower-middle class.