Background: Globally transgender women (TW) are at heightened vulnerability for HIV infection. In Lima Peru, sharp increases in HIV prevalence are seen among TW ages 25 years and older highlighting the need for early HIV prevention efforts for young TW. This study conducted in-depth qualitative interviews to elucidate the social and developmental contexts of HIV vulnerability for young TW in Lima Peru. Methods: Between November 2019 and February 2020, young TW ages 16–24 years (n = 21) in Lima Peru were purposively sampled using in-person (e.g., face-to-face outreach) and online (e.g., social media, networking websites) social network-based methods. Interviews were conducted in Spanish and a rapid qualitative analysis was conducted using a modified immersion crystallization methodology to identify themes. Results: Five themes emerged, informing the conceptualization of a Life Course Health Development Model of HIV Vulnerabilities and Resiliencies: (1) interpersonal contexts (family, school, partners, sexual debut, trans mothers); (2) structural vulnerabilities (poverty, educational constraints, migration, hostile environments, sex work, police violence); (3) concomitant mental health and psychosocial factors (discrimination, violence, depression, suicidality, substance use, life hopes/dreams/future expectations); (4) gender affirmation processes (gender identity development, hormones, surgery, legal name/gender marker change); (5) HIV prevention and treatment barriers (PrEP uptake, HIV care, condom use, risk reduction). Conclusions: Young TW experience formidable developmental challenges associated with transphobia, violence, and pre-maturely facing accelerated milestones. Developmentally and culturally appropriate interventions to mitigate HIV vulnerability in Peru are needed, including those that consider co-occurring stigma-related conditions in adolescence and young adulthood.