Non-equilibrium transport, interfaces, and interfacial mixing play an important role in plasmas in high and low energy density regimes, at astrophysical and at atomic scales, and in nature and technology. Examples include the instabilities and interfacial mixing in supernovae and in inertial confinement fusion, the particle-field interactions in magnetic fusion and in imploding Z-pinches, the downdrafts in stellar interiors and in the planetary magneto-convection, magnetic flux ropes and structures in the solar corona, and plasma thrusters and nano-fabrication. This Special Topic exposes the state-of-the-art research on non-equilibrium transport, interfaces, and interfacial mixing in plasmas, including theory, experiment, and simulations. The works were presented at the invited mini-conference “Non-equilibrium Transport, Interfaces and Mixing in Plasmas” at the 2019 Annual Meeting of the Division of Plasma Physics of the American Physical Society.