This study aims to analyze the national early childhood curricula of South Korea and Sweden through the perspective of education for sustainable development (ESD) and determine the ways of implementing ESD into the curriculum of South Korea. Therefore, frequency–inverse document frequency and network analysis are conducted on the texts of South Korea’s ‘Nuri curriculum’ and Sweden’s ‘Curriculum for Preschool Lpfö 98’ using the R program. The results are as follows: First, South Korea’s curriculum emphasizes attitudes and values, while the Swedish curriculum focuses on practice and action. This highlights the need to add action- and practice-oriented dimensions to the contents of South Korea’s curriculum. Second, the analysis of the degree centrality reveals that, in South Korea, the network takes the form of an intensive connection. In contrast, in Sweden, the network has a wide distribution of words from the socio-cultural, economic, and environmental sectors. This difference suggests that the contents of ESD should be reinforced in South Korea through an integrated approach. Third, South Korea’s contains texts related to students’ interactions with others, while Sweden’s highlights agency. This suggests that South Korea’s curriculum needs to be redesigned to emphasize agency to find an effective way of connecting it to ESD.