The study aimed to determine factors influencing private companies’ adoption of health insurance in Tanzania. The study specifically aimed to explore the awareness of private companies towards the health insurance policy, to examine the compliance to health insurance policy by private companies, and to identify the challenges towards adherence to the health insurance policy by the private companies in Tanzania. The study was descriptive in nature and used a case study design. The study collected data from 100 selected respondents through a stratified simple random sampling technique. Data were collected through interviews, questionnaires, and documentary reviews. Major findings have shown that awareness of private companies toward health insurance policies could be much higher. An average of 96.3% of respondents disagreed with their working companies’ awareness of health insurance policies. This has resulted in low registration for health insurance in private companies involved in the study. However, this finding should not be generalized to other private companies as they may differ in the level of awareness on the significance of accessing employees with health insurance. Hence, it affects their commitment to registering for health insurance. To a greater extent, private companies involved in the study do not comply with health insurance policies. The findings show that 90% of the respondents disagreed that their company operates according to a health insurance policy, 97% percent of the respondents disagreed that their company has the policy to guide the provision of health insurance, 100% of the respondents disagreed that governments guidelines are fair on the provision of health insurance by private companies, and 93% percent of the respondents disagreed on their company’s fulfillment of rules and regulations on health insurance provision. Challenges towards adherence to the health insurance policy by the private companies in Tanzania include unaffordable costs, cumbersome procedures, ignorance of clients and company, poor record management of client’s registration requirements, limited nature of accessing to health insurance services, English language barrier,  limitation of family members registration, lack of commitment among health insurance staff, limitation of age to using health insurance, discrimination of health insurance cards and scheme, and exemption of some medical treatment. The study recommends that private companies have a clear policy to guide health insurance registration. The private company should sensitize employees on the importance of health insurance to increase their awareness. Health insurance schemes should not be restricted to some medical care/treatment. Health insurance companies should have user-friendly procedures for registering clients.