The ozone level in the Republic of Korea has increased over the last 25 years, and an effective control strategy and scientific understanding to support it are needed. In this study, the processes that determine ozone level in Korea are analyzed and the probable future ozone trend are discussed. It was found that the concentration of ozone transported from the upwind area was very high, exceeding Korea’s 8-h ambient air quality standard, whereas the transport of precursor species was not significant. The transport of ozone from the upper troposphere and stratosphere has been episodically significant. Ozone formation mechanisms and the characteristics of precursor species are well studied in the Seoul Metropolitan Area, but remain poorly understood in other areas of Korea. Especially, speciated emission and the concentration characteristics of volatile organic compounds (VOCs) including oxygenated VOCs (O-VOCs) are poorly understood. With climate crisis, it is expected that the ozone level will increase even with the net zero approach. Based on these analyses, recommendations for policy and research directions are made for a short term (<5 years), a mid term (5< <10 years), and a long term (>10 years).