Objectives <p>Research shows that sexual and gender minorities (SGM) have a disproportionate mental and sexual health burden due to frequent, multi-level stigma. Yet, interventions tailored to this population are scarce. This mixed-methods feasibility trial aimed to test an internet-delivered, systematically adapted mindfulness intervention, Mindfulness-Based Queer Resilience (MBQR), to improve mental and sexual health outcomes among SGM young adults with elevated depressive or anxiety symptoms and HIV/STI risk.</p> Method <p>In this single-arm trial, a total of 25 SGM young adults were recruited, of which 19 enrolled in and initiated the intervention. Feasibility and acceptability were assessed using a client satisfaction survey and a session evaluation form, session engagement and attrition, and qualitative data from exit interviews. Participants also completed assessments for psychosocial and behavioral health outcomes, including depression, anxiety, and sexual risk behaviors. Findings are evaluated via a feasibility framework.</p> Results <p>Participants reported that the program had an overall positive impact, specifically on measures of community building, minority stress content, and informal mindfulness practices. The main barriers to engagement included scheduling and time commitment. Exploratory analyses showed that between baseline and post-intervention, participants who attended 6 or more sessions experienced greater improvement in depression, anxiety, condom use, internalized homonegativity, safer sex self-efficacy, and emotion dysregulation in comparison to participants who attended 5 or fewer sessions.</p> Conclusions <p>This early-phase feasibility clinical trial demonstrates proof-of-concept support for an internet-delivered, SGM-tailored program, MBQR to support mental and sexual health among SGM young adults with elevated psychological distress.</p> Preregistration <p>This study was preregistered on clinicaltrials.gov (NCT05540652).</p>