Despite the introduction of a diagnostic code and acceptance of a diagnostic process for sarcopenia as a new health technology in Korea, many practitioners remain unfamiliar with the evaluation of sarcopenia. Thus, the Korean Working Group on Sarcopenia (KWGS) developed clinical practice guidelines for the diagnosis of sarcopenia in older Korean adults. A two-phase Delphi interview comprising 19 questions was conducted with 40 expert panelists, 22 of whom participated in the first round between June and August 2022. The second round of the Delphi interview included the remaining 11 questions that were not agreed upon in the first round. The screening process for sarcopenia includes various questionnaires and examinations used in different research and clinical settings. The diagnostic process for sarcopenia was simplified by combining the steps of case finding and assessment. The Short Physical Performance Battery test was given particular emphasis owing to its multifaceted nature. Regardless of muscle mass, having low muscle strength with low physical performance is considered clinically relevant and newly defined as “functional sarcopenia.” Comprehensive geriatric assessment is important for diagnosing sarcopenia. The KWGS’s clinical guideline aims to facilitate the early detection of sarcopenia by allowing various screening tools to be used in a unified process and reducing confusion about which tools to use for diagnosis. This recommendation expands the conceptual definition of sarcopenia as a complex pathophysiological state in line with the concept of frailty and aims to stimulate further research on the diagnosis and management of sarcopenia in clinical settings.