INTRODUCTION: Unplanned pregnancy continues to be a global reproductive and public health concern among women. This study aimed to investigate whether factors associated with modern contraceptive use differ by age-group among young and older women of reproductive age. METHODS: This was a cross-sectional study conducted among 433 women of reproductive age, with the median age of 25 years (interquartile range: 21-28), and aged between 18 and 49. Data were collected from 10 public health care clinics in Umlazi Township, KwaZulu-Natal, using a structured questionnaire. Data were coded, entered into Epi Data Manager and exported to Stata for analysis. A Pearson's chi-square test and logistic regression models were employed to assess the level of the association between the predictor and outcome variables, and the p-value of 0.05 or lower was considered statistically significant. RESULTS: Most women in the sample (n = 351, 81%) had obtained a secondary level of education, while 53% (n = 230) were unemployed and 89% (n = 387) were single. We found that women with secondary level of education (AOR: 2.89, 95% CI: 0.99-5.38) or a tertiary level of education (AOR 3.80, 95% CI: 1.07-3.53) were more likely to use contraceptive methods compared to women with lower education. Women who experienced unplanned pregnancy (AOR 0.51, 95% CI: 0.22-3.79) were more likely to use contraceptives. Women aged 25-49 years who experienced pregnancy, whether planned (AOR 3.87, 95% CI: 1.08-3.89) or unplanned (AOR 3.60, 95% CI: 2.15-4.19), were more likely to use a contraceptive method. Results showed that the level of education (p = 0.942) and whether one experienced unplanned pregnancy (p = 0.913) were not significant predictors of contraceptive use among women aged 18-24 years. CONCLUSION: Concerted educational efforts to addressing existing barriers deterring women from accessing contraception among young women are necessary. Different groups of women should be targeted with family planning interventions specific to their needs.