This thesis examines the portrayal and significance of science fiction in contemporary British theatre. Analysing twenty-two texts and productions in their original performance contexts, I make critical comparisons between their science-fictional narratives and the anxieties of the present moment, including social instability, accelerating technological innovation, institutional violence, neoliberal exploitation, and climate collapse. By exploring how theatre practitioners are increasingly intervening on matters of national and international urgency via the lens of a speculative tomorrow, this thesis ultimately argues that science fiction constitutes a new method of political engagement within twenty-first century British theatre. This thesis is structured as a series of case studies built around science-fictional subgenres, each of which is mapped across an interdisciplinary scholarly framework. My introduction lays out the broad theoretical concerns and organisational choices that underpin these case studies, before examining the (limited) existing publications in the field and and locating my approach within scholarship allied to the interests of science fiction, such as robots in performance, digital technologies, and the staging of political theory. Opening with an examination of post-apocalyptic plays, chapter one examines how these productions communicate intense social, political and economic anxieties by making links to the familiar yet alien landscape of the modern post-industrial ruin. Chapter two focuses attention on Anne Washburn's Mr Burns (2014) and draws on cultural memory to explore how the play's post-electric narrative intervenes on notions of remembrance, national identity and belonging. Chapter three considers the depiction of the android in contemporary theatre, framing this figure as a posthuman agent that troubles ontological binaries including human/nonhuman, biological/artificial and object/subject. Concentrating its gaze on RashDash and Unlimited's dance-theatre piece Future Bodies (2018), chapter four considers how this production utilised a range of embodied performance choices - including song, dance and movement - to interrogate and resist the technological erasure of the human body. Finally, chapter five examines the staging of dystopia in numerous recent productions by drawing on scholarship concerning precarity and systemic violence. Combining science fiction, theatre studies and wider academic discourse, this thesis both documents an expanding performance practice and pioneers a new interpretation of political representation within contemporary British theatre-making.