Chemical contaminants are accumulating in marine wildlife such as whales, dolphins and turtles, globally. However, we know very little about the effects of contaminants in these animals, mainly due to the ethical and logistical constraints of conducting whole animal toxicity testing on these large, long-lived animals of high conservation significance. However, cell-based bioassays have recently been established to provide an ethical alternative to assessing the effects of chemicals in marine wildlife. With an initial focus on sea turtles, species-specific cytotoxicity bioassays have been developed to investigate various aspects of sea turtle toxicology, including the toxicity of organic and inorganic chemicals, and the effects of chemical pollution within and between foraging populations. Recommendations from this early research included the need to establish cell cultures from more marine wildlife species, development of additional bioassays that measure a wider range of toxicological endpoints, understanding the chemical kinetics within the bioassays, and improved links between cellular responses and effects at the organism and population levels. To address these recommendations, cell cultures from a wider range of marine wildlife species, including sea turtles, dugong and cetaceans, were established and included in Australia's Marine Wildlife Cell Bank. A high throughput micronucleus assay was developed in sea turtle cells, and validated to assess DNA damage in response to chemical exposure. The chemical kinetics of metals was assessed in a dugong cell cytotoxicity bioassay, and illustrated that nominal concentration are not always accurate in marine wildlife cell-based toxicology. A physiologically-based toxicokinetic model was developed to predict the dietary toxicity threshold of cadmium for green turtles, and illustrated that cadmium poses significant risk to many sea turtle populations around the world. Together, these studies have significantly advanced cell-based wildlife toxicology, providing a platform for improved chemical risk assessment in these environmentally, culturally and economically important animals.