Background: HIV testing services (HTS) are a component of HIV prevention and care programs in developed countries and have proven to be a cost-effective way of monitoring the disease, reducing risky behaviours and leading patients to other services. Objective: To determine the prevalence and risky behavioural factors associated with HIV among the attendees of HIV testing services in a part of Ogun state, Nigeria. Methods: This was a descriptive cross-sectional study of HTS clients in health facilities within Ogun State, Nigeria. A multi-stage sampling technique was used for data collection using a pretested, close-ended, interviewer-administered questionnaire. Results: A total of 800 respondents with a mean age of 32.57±10.39 years were surveyed. The prevalence of HIV was 1.6%. The majority (93.6%) of the respondents were sexually experienced. The percentage tested previously among study participants was 5.0%. This significantly comprised those below the age of 18 years (X2 = 22.01, p = 0.0001) and female respondents (Χ2 = 4.84, p = 0.028). Only 21 (2.6%) have had unprotected sex with a casual partner. Significantly more of the female respondent had been involved in this risky sexual behaviour (X2 = 4.52, p = 0.034). Only 7 (0.9%) had sex with multiple sexual partners in the last three months, and 17 (2.1%) were positive for symptomatic STI screening. Conclusion: The prevalence of HIV was low to be 1.6%, and the percentage tested previously was 5.0%. The practice of free HIV screening should be maintained to encourage more people to undergo the test.