The highly energetic East Australian Current (EAC) System is characterised by dynamic frontal zones that form between the EAC jet and its eddy field. Submesoscale processes at these fronts are critical for lateral and vertical mixing, heat and nutrient flux, and biomass increase and export, but are poorly characterised because in situ high-resolution observational data are lacking. Here, we quantify and contrast the kinematic properties of 13 fronts observed in different dynamical regions of the EAC System using high-resolution data from a dedicated shipboard experiment. We show evidence of strain-driven frontogenesis at most fronts, leading to subduction of colder surface waters rich in oxygen and Chl-a. However, strong surface strain or temperature gradients do not always lead to strong biomass subduction. EAC fronts are associated with relatively shallow subduction depths, likely due to strong stratification of surface waters, in contrast to deep-reaching fronts observed in dipole jets between counter-rotating eddies. We reveal that mesoscale context and frontal structure critically govern vertical exchange and vertical transport of biogeochemical tracers, with the greatest percentage of depth-integrated Chl-a below the euphotic layer (75%) in fronts at dipole jets, associated with downward transport of biomass due to ageostrophic motion. This work demonstrates the diversity of fronts in a dynamic, oligotrophic western boundary current and highlights the essential role of frontal processes in nutrient cycling and carbon export. These results illustrate the need for high-resolution observations and models to accurately estimate biogeochemical processes and carbon fluxes across fronts in a western boundary current system.