This dissertation forges a new critical rubric that explores synergies between urban ecologies, technologies, and cultural practices. It argues that contemporary regimes of control as well as forms of effective political intervention converge at the intersection of these fields. The critical framework it develops, biotechnical ecologies, is equipped to examine urban intervention through collective art practices and their speculative digital futures as well as contemporary forms of regulation and limitation at work in the urban landscape. Following an ethnographic methodology, the work is based on extensive research on organizations, artists and activists in Los Angeles and Buenos Aires. Complementing this empirical and site-based research, biotechnical ecologies also proposes alternative imaginings of these two cities and the works it explores within them while attending to their historical and material specificities. The urban media projects engaged include PigeonBlog, a participatory laymen science project designed by Beatriz da Costa that used carrier pigeons to monitor pollution in Southern California; BuenosAiresWord, an interactive web site that allows users to send and receive messages made of letters taken from images of text throughout the city; Buenos Aires Libre, a horizontally-organized group of programmers and computer enthusiasts who are building an autonomous network, apart from the internet, in Buenos Aires; and Machine Project, an arts and media collective and gallery space in the Echo Park neighborhood of Los Angeles.