This paper reports the findings from the first systematic review of the utilization of traditional medicine (TM) in primary health care (PHC) in low- and middle-income countries (LMICs). PHC is an important component of health care and essential for achieving universal health coverage (UHC). For countries where there is a gap in PHC, TM plays a vital role. It is widely used and has the potential to increase the coverage of PHC and UHC. Hence in situations where TM is recognized in a considerable magnitude, there are scarce evidence and minimal regulation on it and TM practitioners (TMPs). This study aims to identify the current situation in the utilization of TM in PHC or UHC in LMICs. A systematic review and thematic synthesis of qualitative and quantitative studies have been conducted. A total of 56 articles met the criteria and were included in the review. In all, 14 analytic themes have been developed including the current use of TM in PHC, higher accessibility of TM, medical pluralism, national health system, national health policy and national health insurance to include TM, including TMPs in the referral system, utilizing TMPs as community health workers, the needs of scientific research on TM and the need for training both TMPs and conventional medical staffs for better collaboration. The study concluded that it is necessary to further focus on TM in the macro level on strengthening the referral system by including TM to establish a comprehensive service delivery network under UHC and in the micro level to focus on training the TMPs and conventional medicine health workers on both areas to attain more in-depth understanding of each other, which can lead to better collaboration and quality patient care.