This report summarizes the highlights of the Gamma-Ray Astrophysics session at the 39th International Cosmic Ray Conference (ICRC 2025). The session, featuring 368 contributions, was organized around three primary themes, including instrumental developments, Galactic sources and emission, and extragalactic sources with their broader astrophysical and cosmological implications. A central driver of the field remains the identification of Galactic PeVatrons and the understanding of the origin and propagation of cosmic rays.
Key highlights include that a growing population of PeVatron candidates have been revealed, extending beyond supernova remnants to include microquasars and young massive stellar clusters; observations of supernova remnants and pulsar halos provide more clues for distinguishing between leptonic and hadronic emission processes; studies of Galactic diffuse emission shed further light on the distribution and propagation of cosmic rays throughout the Milky Way; and studies of extragalactic sources like active galactic nuclei and gamma-ray bursts are being used to probe the extragalactic background light, intergalactic magnetic fields, cosmology and fundamental physics.
Furthermore, technical innovations including novel instrumentation, deep learning analysis techniques, and common software tools are pushing the performance of both current and future experiments. The upcoming deployment of next-generation observatories promises to further revolutionize our understanding of particle acceleration in the Universe in this multi-messenger and multi-wavelength era.