Hypertension is a growing burden in Uganda and other low- and middle-income countries. Appropriate diagnosis services are needed at primary care health facilities to identify, initiate treatment for, and manage hypertension. This study assessed service availability and readiness as well as facilitators and barriers in primary health care facilities for hypertension diagnosis services in Wakiso District, Uganda. In July and August 2019, we conducted structured interviews at 77 randomly selected primary care health facilities in Wakiso District. We used an interviewer-administered health facility checklist modified from the World Health Organization's service availability and readiness assessment tool. We also conducted 13 key informant interviews with health workers and district-level managers. Readiness was measured by availability of functional diagnostic equipment, related supplies and tools, and health provider attributes. Service availability was measured by assessing hypertension diagnosis services. Most (86%; 66 of 77) health facilities offered hypertension diagnosis services and 84% (65 of 77) had digital blood pressure measuring devices; only 69% (53 of 77) had functional blood pressure measuring devices. Lower-level facilities lacked appropriate blood pressure cuffs for use across age groups: 92% (71 of 77) lacked pediatric cuffs and 52% (40 of 77) lacked alternative adult cuffs. Facilitators for diagnosing hypertension included partners that built health facility staff capacity and funds for purchasing hypertension diagnostic supplies; common barriers were nonfunctional equipment, delays in receiving training, and inadequate staffing. The results highlight the need for an adequate supply of devices, routine replacements or repairs, and frequent refresher training for health workers.