Despite the enormous potential of social media for health promotion, there is an inadequate evidence base for how they can be used effectively to influence behaviour. In Australia, research suggests social media use is higher among Aboriginal and Torres Strait Islander people than the general Australian population; however, health promoters need a better understanding of who uses technologies, how and why. This qualitative study investigates what types of health content are being shared among Aboriginal and Torres Strait people through social media networks, as well as how people engage with, and are influenced by, health-related information in their offline life. We present six social media user typologies together with an overview of health content that generated significant interaction. Content ranged from typical health-related issues such as mental health, diet, alcohol, smoking and exercise, through to a range of broader social determinants of health. Social media-based health promotion approaches that build on the social capital generated by supportive online environments may be more likely to generate greater traction than confronting and emotion-inducing approaches used in mass media campaigns for some health topics.