With the broad commercialization of microelectronics, 5G communication, and new energy vehicles, the demand for polymer composites with high thermal conductivity is increasing. Carbon‐based nanomaterials have high thermal conductivity, are lightweight and low‐cost, and have been widely studied as thermally conductive fillers for composites. This paper focuses on carbon‐based thermal conductive fillers in polymer composites. It summarizes the treatments of functionalization, directional arrangement, and dispersion of carbon‐based nanofillers. Moreover, from the perspective of nanocarbon, we divide hybrid nanofillers into three categories: carbon/carbon, carbon/ceramics, and carbon/metal for the first time, and we discuss the thermal conductive effect of these hybrid fillers. Finally, we discuss potential areas for future research and development of thermal interface materials.This article is protected by copyright. All rights reserved.