This paper provides a systematic overview of the psychosocial contribution to decarbonization studies and critically discusses current trends. Following the PRISMA protocol, we reviewed 404 articles informing how socio-psychological processes affect decarbonization, and vice versa, and highlighting research gaps and biases. Contrary to criticisms about methodological individualism and reductionism of socio-psychological research on sustainability, the review illustrates that the field is equally attentive to psychosocial processes operating at different levels, including the individual (e.g., attitudes, stress, environmental concerns), community (e.g., collective identity, justice, sense of place), and socio-cultural levels (e.g., social norms, values, memory). However, evidence shows some problematic trends in the literature: (i) A bias toward specific agents and geographies, which overlooks mesoscale actors (e.g., media, unions, NGOs) and developing and eastern countries; (ii) instrumental and normative views of transitions, which coincide with a prevailing focus on cognitive processes and a selective bias toward technologies, policies, places, and natural resources conceived as instrumental to decarbonization. This also emphasizes how biophysical processes, people–nature relationships, and the role of emotions in understanding the psychology of agents and decarbonization processes are almost absent; (iii) a research gaze normatively oriented toward the future, which risks neglecting continuity–discontinuity dynamics and the timing and pace of transitions.