Background: Health insurance coverage ensures protection from catastrophic health-care expenditure, especially to the underprivileged sections of society. Health insurance schemes such as Ayushman Bharat are coming up in addition to the existing schemes such as Rashtriya Swasthya Bima Yojana in India. The objectives are to find the health insurance coverage and its impact on out-of-pocket (OOP) expenditure for public sector tertiary health-care hospitalization. Methods: A cross-sectional study was conducted at a tertiary care hospital in Kerala. Insurance coverage was assessed among patients seeking inpatient care in various medical and surgical departments. OOP expenses incurred for those receiving and not receiving insurance coverage were compared. In addition, factors influencing enrolment and availing of insurance schemes were determined. Results: The coverage of health insurance was found to be 74%. Awareness campaigns and activities of local self-government (LSG) departments were the important reasons for enrolment and availing, respectively. Significantly lower OOP expenditures occurred in insured persons with regard to expenses incurred for treatment procedures ( P = 0.019), investigations ( P = 0.004), and medicines ( P = 0.001). Among the enrolled patients, 45% expressed dissatisfaction regarding available services. Conclusion: A quarter of patients still remain out of insurance coverage. All patients are incurring OOP expenditures, though the insured patients have significantly lower OOP expenses. The role of primary care providers and LSG is pivotal in creating awareness and ensuring enrolment. Availing services depend on the availability of resources at the respective institution. Improvements in enrolment and use of health insurance should ultimately result in improved patient satisfaction.