Background: Risky sexual behaviour (RSB) among key populations pose a significant risk of human immunodeficiency virus (HIV) infection but remains understudied. Objectives: We assessed the prevalence and factors associated with RSB among key populations living with HIV (KPLHIV) in the post-conflict region of northern Uganda. Methods: We designed a cross-sectional study using secondary data, with the outcome as RSB defined as having multiple sexual partners, or condomless sex in the past 3 months, or sexual intercourse with a commercial sex worker in the past 3 months, or sexual intercourse under the influence of substance use in the past 3 months. We used modified Poisson regression to determine factors associated with RSB, reported as adjusted risk ratio (aRR) with 95% confidence interval (CI). Results: We studied 165 participants and 122 (73.9%) reported RSB and this was more likely among heterosexual females (aRR, 2.39; 95% CI, 1.54-3.71), the married (aRR, 1.92; 95% CI, 1.42-2.49) or separated participants (aRR, 1.47; 95% CI, 1.21-1.79), and transgender persons (aRR, 3.71; 95% CI, 2.05-6.71).Conclusions: RSB is highly prevalent among KPLHIV in northern Uganda so they should be targeted with HIV prevention and behavioural interventions to prevent potential HIV transmission to the general population. Keywords: Key populations; men who have sex with men; people who inject drugs; commercial sex workers; risky sexual behaviour.