Background Belize has one of the highest human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome prevalence rates in Central America, with women of reproductive age being particularly vulnerable to HIV. Therefore, this study examined the factors associated with HIV testing among women of reproductive age in Belize and trends in HIV testing in 2006, 2011, and 2015–2016. Methods Cross-sectional data were analyzed using three Belize Multiple Indicator Cluster Surveys. The number of participants were 1,675, 4,096, and 4,699 women aged 15–49 years in 2006, 2011, and 2015–2016, respectively. We used variance-weighted least-squares regression to estimate annual changes. Multivariate logistic regression analysis was performed to evaluate the associated factors. Analyses were conducted using Stata version 15, and weights were applied for generalization to the population. Results HIV testing rates increased from 47.7% in 2006 to 66.5% in 2015, with an average annual change of 0.082 (95% confidence interval: 0.07–0.09). Logistic regression models showed that women aged 15–24 years were less likely to have been tested for HIV compared to women aged 25–34 years. Women from the Mayan ethnic group were less likely to have been tested than those from other ethnic groups. Compared to women who spoke Spanish, those who spoke English/Creole were more likely to have been tested for HIV; additionally, those who spoke minority languages were less likely to have been tested. Being married and having given birth were associated with increased odds of HIV testing. Living in rural areas and households with the poorest wealth indices were associated with decreased odds of being tested for HIV. Women with good HIV knowledge and accepting attitudes towards people living with HIV were more likely to be tested. Conclusions From 2006 to 2015, HIV testing in women of reproductive age showed an increasing trend in Belize. We recommend interventions to expand HIV testing for women of reproductive age in Belize, particularly those aged 15–24 years, speaking minority languages, living in rural areas, and having a low socioeconomic status.