Live imaging enables direct observation of dynamic biological processes, capturing their progression from molecular to organismal scales in space and time. Through high-resolution observation, it provides a powerful means to decode biological complexity by revealing dynamic behaviors, spatial patterns, and regulatory changes. This review illustrates the application of live imaging in investigating complex biological processes with spatiotemporal resolution and mechanistic insight. We first highlight the analytical power and integrative strategies of live imaging, and then summarize recent advances that further extend its capacities. We then focus on four complex processes—cell proliferation, lineage regulation, morphogenesis, and atlas construction—to elucidate how live imaging contributes to their decoding through representative studies. We also discuss the conceptual and practical limitations that currently constrain the full interpretive potential of live imaging, underscoring the need for deeper integration between observation, perturbation, and modeling. Looking ahead, live imaging will benefit from both technical refinement and advances in data standardization and visualization, functional quantification, multiscale integration, and the discovery of generalizable principles. Together, these directions advance a more integrative and mechanistic understanding of complex biological processes.