The emergence of synthetic biology marks a significant paradigm shift in humanity’s engagement with the natural world, transitioning from exploitation and conservation to deliberate ontological redesign. This review builds on the concept of synthetic biology as a “postmodern technology of care” by critically examining its philosophical foundations, operational mechanisms, and ethical ramifications. We contend that synthetic biology enacts a form of ontological care, aiming to address suffering and existential threats not by modifying environments or behaviors, but by re-engineering the biological essence of organisms to enhance their fitness within human-altered contexts. Drawing on literature from bioethics, science and technology studies (STS), environmental philosophy, and molecular biology, this review analyzes three principal mechanisms of ontological care: (1) Metabolic Gatekeeping, where organisms are engineered for hyper-efficiency in controlled bioproduction systems; (2) Predetermined Ecologies, where gene drives and genetic biocontrol establish human-designed population dynamics in wild systems; and (3) Evolutionary Triage, where assisted evolution and de-extinction projects prioritize genetic malleability over ecological resilience. We identify the central ethical dilemma as the “Care-Control Paradox,” in which benevolent objectives such as species preservation or disease eradication are pursued through extensive biological control and simplification. The review concludes by considering alternative frameworks, including “relational care” and “prosthetic biology,” that may foster more collaborative and less imperialistic approaches to the more-than-human world. Ultimately, we argue that the most profound impact of synthetic biology may reside not in the organisms it produces, but in the new, technologically mediated ontology of life it establishes.