BACKGROUND Knee osteoarthritis (OA) is a chronic joint disease characterized by pain, swelling, and limited knee activity. Numerous studies have reported the efficacy and mechanism of physical activity in patients with knee OA. However, bibliometric analyses of physical activity and knee OA are rare. This study aimed to discuss the hotspots, frontiers, and trends in physical activity and knee OA research using bibliometric methods to provide valuable information for future research. MATERIAL AND METHODS Relevant literature was obtained from the Web of Science Core Collection database from 2000 to 2021. English-language articles and reviews were selected. CiteSpace (6.1.R2), a bibliometric analytical tool, was used to analyze the countries, institutions, journals, authors, keywords, and references. RESULTS A total of 860 papers were obtained. Publications and citations have increased over the years. The most productive country, institution, author, and journal were USA, the University of Melbourne, Bennell KL, and Osteoarthritis and Cartilage. The author and journal with the most citations were Fransen M and Osteoarthritis and Cartilage. McAlindon TE et al's paper had the most citations and the strongest burst. Two references for the latest bursts were published by Fransen M et al. and Bartholdy C et al. The top 4 keywords were "hip," "knee osteoarthritis," "pain," and "older adult." The keywords for the latest burst were "guideline" and "risk." CONCLUSIONS Over the past 2 decades, research on physical activity in knee OA has received increasing attention. This study identified research hotspots and development trends, providing meaningful information for researchers.