Background: Trans women in Vietnam are among the most vulnerable groups with high HIV risk and limited access to care. TransAction is an evidence-based intervention to reduce trans women's HIV risks and increase social support and access to care.Aims: The aim of this study was to adapt TransAction to the specific needs of trans women in Vietnam. Methods: This study was conducted in Ho Chi Minh City from November 2020 through June 2021 Using the ADAPT-ITT framework, interviews, focus groups, and community advisory board meetings were conducted with trans women, service providers, and community members to better understand Vietnamese contexts of gender transition, HIV risks, and service gaps. Feedback was solicited on TransAction content and format adaptation. Results: Trans women in Vietnam faced unique challenges related to family norms, policy and regulatory constraints, and limited transgender-specific or gender-inclusive services. TransAction was modified to accommodate identified challenges and needs, and intervention components to enhance family support were added. Strategies to cope with stigma and seek support and services were adapted to Vietnamese culture and policies. Discussion: Post-adaptation interviews and focus groups demonstrated strong feasibility and acceptability for the adapted intervention, which can potentially be used to reduce Vietnamese trans women's HIV risks and increase their social support.