Blood tests (BTs), specifically liver and/or kidney function tests, are employed in Korean Medicine (KM) practice to ensure the safety of herbal medicine. The widespread concomitant use of conventional and herbal medicines in South Korea requires BTs due to the unpredictable liver injury and drug–herb interactions. However, BTs ordered by Korean Medicine doctors (KMDs) are currently not covered by the National Health Insurance (NHI), which further leads to a lack of data on the demographics and utilization of BT in KM practice. This study surveys the frequency and features of BT utilization through a national sampling of KMDs. Between February 10 and 20, 2023, a questionnaire was developed and electronically distributed to 25,574 KMDs across the nation, comprising all licensed and qualified to practice KM at the time of the survey. We assessed respondents’ characteristics, perceptions, current use and usage patterns, including frequency and indication of BT, and unmet BT needs. Of the 830 KMD (3.25% of all the licensed) respondents, 363 incorporate BTs in their workups, while 467 do not. Liver function tests (n = 351) are the most common, followed by kidney function (n = 235) and diabetes (n = 188) tests. The time of ordering BT varied by institution, with KM hospitals most often in “the patient’s first visit” (45.71%), and KM clinics “before and after prescription of herbal medicine.” (43.75% in specialized clinics; 36.95% in non-specialized). The purposes of ordering BTs were to complement the assessment of health conditions (67.22%), monitor herb-induced liver injury (58.68%), and follow up after KM treatment (55.10%). Meanwhile, 97% of the current non-users of BT hope to use it in the future, with 90.36% suggesting that BTs be covered by the NHI. Understanding the current BT practice pattern may guide the creation of guidelines for proper BT usage in KM practice. In addition, stakeholders must recognise the importance of BTs in real-world KM practice to monitor patients’ condition or reactions after herbal medicine administration.