First Nations people and communities have long been championing the provision of holistic, self-determining, culturally safe, and responsive health care. In April 2016, a catastrophic rise in illicit drug overdose deaths in the province of British Columbia (BC), Canada, led to the declaration of a public health emergency. Due to the compounding historical and ongoing impacts of colonialism, including trauma and inequitable access to health services, First Nations people in BC are disproportionately impacted by this crisis. In response, the First Nations Health Authority created Not Just Naloxone (NJN), a train-the-trainer workshop designed to build Indigenous harm reduction knowledge and skills within First Nations communities. This article describes the NJN program and presents the results of a follow-up evaluation of 37 participants from six NJN workshops held between December 2017 and October 2018. Core strengths of the training included an Indigenized approach and the opportunity to build networks of support. Respondents reported increased knowledge and confidence presenting about harm reduction and feeling more prepared to respond to overdoses. Areas for improvement included maintaining up-to-date training materials and navigating emotional triggers for participants. Trainees went on to train over 2,400 community members in naloxone and Indigenous harm reduction, and reported that communities’ awareness and attitudes around harm reduction began to change. Challenges providing community trainings included buy-in from local leadership and persistent abstinence-based beliefs. This evaluation demonstrates the impact of holistic, culturally safe harm reduction training and the need for a connected community of Indigenous harm reduction champions.