The objective of this research is to establish a better understanding of the current landscape of online learning research and development. Data were collected from the Web of Science (including SCI-EXPANDED, SSCI, and AHCI), which contains articles published from 2004 to 2022. A total of 25,382 pieces of data were collected. The data were visualized and analyzed using Citespace. The results show that the USA, China, and England are the main research countries in online learning; the Open University, Nanyang Technology University, and Monash University are the main research institutions; and Hwang Ggo-Jen, Huang Yueh-Min, and Chen Nian-Shing were the lead researchers. Major research topics in the field of online learning include MOOCs, flipped classrooms, COVID-19, computer-supported collaborative learning, the technology acceptance model, communities of inquiry, and distance learning. Meanwhile, each topic includes some classical literature. Computers & Education, Educational Technology Research and Development, the Internet, and Higher Education are three highly cited journals. Research hotspots mainly include three types of terms: student-related, learning-system-related, and teacher-related. Finally, we proposed further study ideas for future paths.