AbstractMeasures for meditative mindfulness have been developed and validated. However, relatively little attention is paid to a socio‐cognitive definition of mindfulness, also known as Langerian mindfulness. Socio‐cognitive mindfulness is an indispensable perspective for studying mindfulness within a social context. In this research, we conducted one pilot and two formal studies online, with a total of 831 Japanese participants, to develop and validate the Japanese version of the Langer Mindfulness Scale (LMS‐J). In the pilot study, we confirm the dimensionality via exploratory factor analysis. In Study 1, confirmatory factor analysis and test–retest reliability based on a 4‐week interval were performed. In Study 2, convergent and discriminant validity were tested by examining the relationships between Langerian and meditative mindfulness, Big Five personality traits, and life satisfaction. Overall, the results suggest that the factor structure of the LMS‐J is similar to its original version, and the LMS‐J is a reliable and valid measure. Therefore, the LMS‐J can be used to measure Langerian mindfulness in the Japanese population, especially for research in individual development within a social context.