Background <p>The rapid growth of the world’s population presents significant socio-economic and health challenges. Family planning programs, including the promotion of injectable contraception, are critical to address this issue in Indonesia. This study aims to analyze the relationship between knowledge, attitude, and practice regarding injectable contraceptive use, identifying which factor is most influential. This study focuses on Palembang, an urban setting that offers a relevant context for exploring these issues as it is representative of many urban areas in Indonesia.</p> Methods <p>A cross-sectional study was conducted at a Public Health Center in Palembang in October 2024, involving 104 respondents who met the inclusion criteria. The variable “practice” was operationalized as the respondent’s current or past use of any contraceptive method, measuring their direct experience. Relationships between variables were analyzed using Chi-Square tests and prevalence ratios with IBM SPSS Statistics 22.</p> Results <p>This study showed no significant relationship between knowledge and the use of injectable contraception (PR = 1.801 and p-value = 0.311), a significant relationship between attitudes and the use of injectable contraception (PR = 2.786 and p-value = 0.029), and a significant relationship between practice and the use of injectable contraception (PR = 17.795 and p-value = 0.000). The most influential factor in the use of injectable contraception was practice (adjusted PR = 24.568 and p-value = 0.000).</p> Conclusion <p>Practice is the most significant factor influencing injectable contraception use. This key finding calls for a strategic reorientation of family planning programs towards interventions that promote the initiation and maintenance of contraceptive practice, rather than focusing primarily on knowledge dissemination.</p>