Climate services (CS) often face usability challenges, with many climate information products lacking uptake and use. Integrating local knowledge (LK) can enhance the credibility, salience and legitimacy of CS. Although international frameworks increasingly call for incorporating LK, how it is studied and applied in practice remains unclear. We conducted a systematic review of CS and climate change adaptation literature (119 articles) and operational CS projects (22 projects) to examine where LK is explored, whose knowledge is considered, and how it is used within CS.