This paper examines how issues related to abortion have historically been influenced by population control policies in South Korea and how the contemporary reproductive justice movement in South Korea has contributed to social change. On April 11, 2019, South Korea's Constitutional Court ruled that the ban on abortion was unconstitutional. As a result, South Korea's legislature must revise the 66-year-old anti-abortion law by December 31, 2020. This historic decision was closely related to the advocacy of a number of feminist groups, doctors' organizations, disability rights groups, youth activists, and religious groups in South Korea, who collectively formed the Joint Action for Reproductive Justice (Joint Action) in 2017. This paper describes the activism and actions of Joint Action as a key part of reproductive justice movements in Korea. Joint Action was initiated by an organization for women with disabilities, and once formed, they worked collectively to frame abortion as a social justice issue that goes beyond the pro-choice versus pro-life binary. By focusing on the composition, strategies, and main agenda of Joint Action, this paper analyzes how Joint Action influenced the Constitutional Court's 2019 decision to decriminalize abortion in South Korea and how the court established that it is the government's responsibility to ensure every individual's reproductive health and rights.