Urinary tract infections are complications found mostly in older adults undergoing hip surgery. However, little is known about the impact of urinary tract infections on health at after post-hip fracture surgery, particularly in Thailand. This prospective study investigated the prevalence of urinary tract infections and their impact on length of stay, functional ability, re-admission, surgical site infections, and in-hospital mortality. The participants were 120 older adults undergoing hip surgery at four tertiary care hospitals in Bangkok, Thailand. Instruments for collection the data were the Demographic Data Questionnaire, Health Outcome Data Record Form—length of hospital stays, surgical site infections, re-admission, and in-hospital mortality, and the Hip Disability and Osteoarthritis Outcome Score. Data were analyzed using descriptive statistics and Firth’s logistic regression. Results demonstrated that the prevalence of urinary tract infections was 28.32%. Significantly, older adults who developed urinary tract infections had a 2.88-fold increased the risk of impaired functional ability four weeks after surgery and a 3.21-fold increased the risk of re-admission to the hospital compared to those without urinary tract infections. Findings suggest that nurses should continually evaluate urinary tract infections and related factors from admission to post-discharge, as urinary tract infections profoundly affect health outcomes. Strict compliance with guidelines or strengthening post-acute care services to prevent urinary tract infections and its consequences is recommended to promote and restore health, especially functional ability in older adults undergoing hip surgery.