The total fertility rate in Mali (6.2) is the third highest in the world. Despite sociocultural similarities, the total fertility rate in neighboring Senegal is 4.2. The aim of this study is to identify factors which may help to explain the differences between the two countries and which may thereby inform family planning policy in Mali. A cross-sectional study was conducted with a convenience sample of 602 married women aged 16–50 from urban and rural sites in southern Mali and Senegal. A total of 298 respondents from Mali and 304 from Senegal completed a structured questionnaire between July and October 2018. In total, 11.1% of the Malian respondents and 30.9% of the Senegalese respondents were currently using family planning, and 34.6% and 40.5%, respectively, had ever used a modern family planning method. Pressure from husbands was cited as a primary influence for having more children (in 50.3% of Malians and 45.4% of Senegalese, p = 0.000). Women’s age, education level, and knowledge of different contraceptive methods were associated with ever use of contraceptives. After adjustment for confounders, discussing family planning with one’s husband was the strongest predictor of contraceptive use among both Senegalese (OR = 3.4, 95% CI (1.9–6.3), p = 0.000) and Malian respondents (OR = 7.3, (4.1–13.3), p = 0.000).