Consistent condom use can prevent HIV infection, yet levels of condom use are low in many settings. This paper examines determinants of inconsistent condom use among 905 women enrolled in a high-risk cohort in Kampala, Uganda, who reported sexual intercourse with paying clients in the last month. Among these, 40% participants reported using condoms inconsistently with paying clients in the past month. The most common reason for inconsistent condom use was client preference. Factors independently associated with inconsistent condom use included: sex work not being the sole source of income [adjusted odds ratio (aOR) = 1.54; 95% confidence interval (CI): 1.13–2.09], sexual debut before 14 years (aOR = 1.46; 95% CI: 1.09–1.96), daily consumption of alcohol (aOR = 1.90; 95% CI: 1.26–2.88) and being currently pregnant (aOR = 2.11; 95% CI: 1.25–3.57). Being currently married (aOR = 0.36; 95% CI: 0.18–0.73) and a higher number of sexual partners per month (p-trend = 0.001) were associated with a lower risk of inconsistent condom use. Targeted programmes should be developed to promote consistent condom use in high-risk women, alongside interventions to reduce alcohol use.