South Korea’s economy took off in the 1960s. It became a member of the Organization for Economic Cooperation and Development (OECD) in 1996 and a high-income country as defined by the United Nations in 2001, achieving catch-up as a latecomer economy. An analysis of South Korea’s economic development since its founding using the A-C theory framework shows that since the 1990s, South Korea has maintained a high degree of political governance cohesion and economic accessibility, with its level of opening-up, represented particularly by external economic accessibility, being remarkably high. South Korea’s successful experience as a classic model of dual-pillar development featuring “cohesive political governance+internal and external economic opening-up” provides valuable insights for late-developing economies in areas such as political governance, economic openness, and market cultivation.