This paper focuses on empirically understanding the growth patterns of Sudokwon, the metropolitan area of South Korea, and draws out some policy implications for Seoul. In detail, this study carefully defines the metropolitanization of Sudokwon as a concept that includes not only spatial expansion but also increased interconnectivity between regions. Rather, this research proposes that the latter is a key phenomenon of Sudokwon’s metropolitanization today unlike in the past when the former was the mainstream. In this regard, in this study, changes in residential and commuting movements across borders in the area of Sudokwon are scrutinized and the actual conditions of its growth patterns are identified. Moreover, the examination of the changes in socioeconomic movements of Seoul citizens is also carried out to reinterpret the phenomena of Sudokwon’s growing into the one area. At the end, based on the empirical analysis results, this paper discloses that when establishing strategies to cope with metropolitanization, the ultimate goal is to strengthen inter-regional connectivity and a place-based approach is desirable.