Semiconductor packaging materials play a critical role in the development of semiconductor devices. They not only provide reliable protection and support, but also contribute to the electrical connection between the chip and the external circuit. Among many choices of packaging materials, polymer‐based nanocomposites have become the mainstream candidate due to their low cost, easy processability, and tunable properties. Materials with low dielectric constant and dielectric loss, high glass transition temperature, fast thermal conductivity, suitable coefficient of thermal expansion, low viscosity, and good processability are commonly required in semiconductor packaging, yet most polymers do not meet these criteria. Therefore, modulation of the polymer matrix, introduction of suitable fillers, and modification of the filler surface are often effective approaches to enhance the performance of the composites. Here, the authors first review current research progresses of polymer‐based nanocomposites for five different types of packaging applications, namely moulding compounds, thermal interface materials, underfills, die attach materials, and substrates. The authors then present prospects of developing next‐generation polymer‐based nanocomposites for advanced semiconductor packaging and propose some suggestions to solve the existing challenges.