Telemedicine has been appreciated as a smart solution to bridge the gaps in the delivery and coverage of healthcare worldwide. With the great impetus to integrate this service into primary healthcare facilities, evaluating its usability should be an ongoing process. This study aimed to quantitatively evaluate the usability of telemedicine from the primary healthcare physicians’ perspective in Oman. The evaluation was conducted using a cross-sectional study design. A self-administered online questionnaire was developed and validated as a scale to evaluate the usability of telemedicine as a safe and useful communication channel and outpatient record. Following a pilot study, the questionnaire was distributed to a sample of primary healthcare physicians who ran telemedicine clinics in Oman during 2020-2022. The questionnaire was completed by 143 primary healthcare physicians from different governorates. The total mean scale and subscale scores were computed. In addition, the frequency distribution of responses to each question was presented. The results showed that the total mean scale score of the usability of telemedicine in our clinics was 3.43/5.00. The subscale scores of the usability of telemedicine as a safe and useful service, the usability of telemedicine as a communication channel, and the usability of telemedicine as an outpatient record were 3.42/5.00, 3.23/5.00, and 3.99/5.00, respectively. In conclusion, the current telemedicine service in Oman’s primary healthcare facilities has some usability features, but there is still much room for improvement. With logical reasoning, a framework of potential determinants was inferred and proposed to improve the usability of telemedicine services in the future and comply with the principles of biomedical ethics.