The purpose of this study was to characterize the social networks of female sex workers (FSWs) living with HIV in the Dominican Republic (DR) and to examine the association between daily drug use and network risk profile. The study employed a micro-longitudinal observational design using a 7-day mobile health (mHealth) daily diary to collect daily substance use behaviors and social network data was collected at study enrollment. A series of crude and adjusted modified log-Poisson repeated measures regression models with generalized estimating equations (GEE), clustering by individual with a compound symmetry working correlation structure were fit to estimate the relative risks and 95% confidence intervals. Controlling for individual level factors, findings revealed that FSWs with more network members who were drug users (≥ 3) and more network members who were sexual partners and also drugs users (≥ 2) were 8.89 (95% CI 2.62, 30.22) and 6.08 (95% CI 1.20, 30.92) times more likely to engage in daily drug use compared to women with small drug and sex and drug networks. Study findings demonstrate the role high risk networks have on risk behaviors. Results may be used to inform interventions that focus on modifying negative social ties, creating and/or improving existing positive support relationships, and integrating drug use harm reduction promotion within HIV treatment programs.