Background: In 2019, global hypertension cases exceeded 1 billion, marking a twofold increase since 1990. In Kenya, hypertension affects 24% of the population and unfortunately, its control remains suboptimal and in particular, Kiambu County. Identifying the interconnected factors impacting hypertension control is crucial for developing effective interventions. This study aimed to evaluate these factors among Thika Level 5 Hospital patients in Kiambu County. Methods: A cross-sectional study design was used, utilizing mixed methods. The quantitative approach involved administering a structured questionnaire, while the qualitative aspect utilized a key informant interview guide. The sample size was determined using Cochran’s formula. An additional 30% of the calculated sample size (385) was included, resulting in a response rate of 98.6%. Systematic random sampling was employed to meet the required sample size. The study population consisted of hypertensive patients at Thika Level 5 Hospital in Kiambu County. Results: This study included 493 participants, with the largest proportion (32%) aged 55-65 years. The study identified a prevalence of uncontrolled hypertension at 73.6%. Factors strongly associated with uncontrolled blood pressure included respondents’ level of knowledge, choice of transport, and greater distance to healthcare facilities (χ2 (df=8), 78.67, p=0.001). The emerging theme from the key informants on patients’ knowledge about hypertension was “inadequate knowledge”. Conclusions: Recognizing that patient knowledge is a predictor of uncontrolled blood pressure, healthcare providers should consistently offer patient education. Additionally, the risk of uncontrolled blood pressure rises with greater distance from healthcare facilities, necessitating increased healthcare accessibility by the Ministry of Health.