Indigenous self-determination, land rights and caring for Country programs are enabling Indigenous peoples across the world to re-establish customary roles in biodiversity conservation and cultural fire management. In Australia, Indigenous-controlled lands form the majority of the protected area estate, harbour almost 60% of listed threatened species and maintain high levels of biodiversity. This study used cross-cultural (Indigenous and Western academic) methods to monitor the impact of Indigenous cultural burning v. wildfire on the threatened plant, Backwater grevillea (Grevillea scortechinii subsp. sarmentosa). Cultural burning resulted in lower mature grevillea mortality and less impact on reproductive output than wildfire. Both fires stimulated a mass germination but the cultural burn preserved a multi-aged population while the wildfire killed 99.6% of mature shrubs. Comparison of fuel load changes resulting from cultural burning, hazard reduction burning and wildfire indicated that fuel loads were reduced by all fire treatments, although the cultural burn was less severe than other fires. Our case study of the Backwater grevillea and its Banbai custodians provides an example where Indigenous rangers have adopted a plant into their cultural management framework. They are conserving this threatened species using culturally driven, holistic management that is locally focused and supported by cross-cultural knowledge.