Postnatal care is the care provided to the mother immediately after delivery of baby and placenta. The care is spread across a minimum of four postnatal visits packaged as focused postnatal care. During this period the health worker takes the opportunity to provide essential services geared towards offering promotive, preventive and curative services to both mother and baby. Approximately 800 mothers die daily globally due to pregnant related causes, some are direct and others are indirect causes. This translates to about 600, 000 maternal deaths annually in the global arena. Objective: We set to carry out a research to establish determinants of utilization of postnatal services among postnatal mothers in Kakamega County. Study design: This was a descriptive cross-section study involving 215 participants recruited from three sub-county hospitals. Sampling technique: We used a simple random sampling followed by systematic sampling to select study subjects who were consented. Data was collected using a questionnaire and entered into a data base and analyzed using SPSS version 21. Results: Variables that were significantly associated with utilization of services included: occupation, health facility, time taken to hospital, number of antenatal clinic attendance and number of postnatal clinic attendance. There was a significant association of services offered and utilization (p<0.05). We concluded that majority of participants utilized postnatal services with the number of ANC, PNC and occupation were significantly associated with utilization of postnatal services. The uptake of cancer of cervix screening was low compared to other services and therefore the study recommends the county government of Kakamega to introduce strategies that may accelerate the uptake of this service.