Mobile health (mHealth) offers a practical route to extending maternal healthcare to underserved populations, yet its uptake in many developing settings remains modest and unevenly distributed. This study assessed the adoption of mHealth services for maternal care among reproductive women and healthcare professionals in Osun and Ondo States of Southwest Nigeria. The specific objectives were to identify the types of mHealth services available, determine the extent and level of adoption, evaluate the contextual factors influencing adoption, and examine the perceived effects of adoption on maternal health outcomes. Grounded in the Unified Theory of Acceptance and Use of Technology and the socio-ecological model, the study used a mixed-method design. Two structured questionnaires were administered to 384 reproductive women aged 15 to 49 years and 60 healthcare professionals across facilities selected by a population proportion to size procedure. Data were analysed using descriptive statistics, the chi-square test, and binary logistic regression at the 0.05 level of significance, with odds ratios and 95 percent confidence intervals reported. About 65 percent of facilities had adopted mHealth, with phone calls the dominant modality, used currently by 73.1 percent of facilities. Among reproductive women, however, adoption was very low: phone calls and WhatsApp calls were each adopted by 4.7 percent, text messages by 3.1 percent, and WhatsApp messages by 2.1 percent, while video-conferencing applications were largely unknown and unused. Self-rated competence with these tools was nonetheless high, indicating that the adoption gap reflects awareness, social, and contextual barriers rather than digital skill. Adoption among women was significantly associated with age, level of education, occupation, household monthly income, and state of residence, while family type, household size, and gender of household head were not significant. Healthcare professionals rated mHealth as sometimes helpful for excessive bleeding (mean 3.23), miscarriage (3.07), and prolonged labour (3.07). The study concludes that the application of mHealth for maternal care remains inadequate and adoption among reproductive women is limited despite high availability and competence, and it recommends targeted awareness, provider engagement, the introduction of under-used modalities, and infrastructure measures to close the adoption gap.