This study used mixed-methods design to explore BBVs/STIs risk and protective practices among international students in Sydney from East Asian and sub-Saharan African countries and territories, before and during the COVID-19 pandemic. Semi-structured interviews were conducted with twenty international students from East Asia (N=10), and sub-Saharan Africa (N=10) to explore sexual practices, and the socio-cultural factors shaping these practices. Additionally, an online anonymous survey (N=149) was conducted to investigate BBVs/STIs protective practices and their predictors. Semi-structured interviews were also conducted with sixteen international students from East Asia (N=7), and sub-Saharan Africa (N=9) to explore how the COVID-19 pandemic impacted BBVs/STIs risks. Qualitative data were analysed using reflexive thematic analysis method while quantitative data were analysed using logistic regression model at 0.05 alpha level. Analysis of the interviews data revealed that participants perceive sexual norms in Australia as permissive and casual. In line with sexual script and social norm theories, some participants indicated that it is near impossible to maintain sexual abstinence norm in Australia. Interestingly, some participants hold the view that BBVs/STIs are rare in Australia. This perspective could impact BBVs/STIs risk practices as indicated in interviews data around condomless sex. Condomless sex was a common BBVs/STIs risk practice among participants who are sexually active in Australia. Factors shaping this practice include curiosity, condom-related stigma, alcohol use, seeking greater intimacy and pleasure, and gender stereotypes. Findings from the quantitative data showed that sexual acculturation was the only modifiable predictor of BBVs/STIs protective practices (OR = 0.883, 95% CI = 0.820–0.952). Thus, participants with greater acculturation were less likely to report BBVs/STIs protective practices. Moreover, findings from the qualitative data indicated that pre-COVID BBVs/STIs risks were elevated by the COVID-19 pandemic among some sexually active participants. The findings of this thesis provide evidence for contextualised sexual health services for international students from more conservative cultures. Such services should be cognisant of perceptions around sexual norms with the aim of supporting international students to manage migration-related changes in their sexual practices in a safe manner. Additionally, it is vital to address structural barriers to reduce risk, and strengthen BBVs/STIs protective practices among this population.