Despite growing interest in individual goal disclosure by both consumers and enterprises, limited research has investigated the underlying motivations behind goal disclosure on social media and its impact on goal attainment. This study aimed to elucidate the foundational structure of user motivations for goal disclosure on social media (UMGDSM), develop a reliable and valid scale to measure these motivations, and uncover the relationship between various goal disclosure motivations and goal attainment. To achieve these objectives, we conducted an in-depth interview qualitative study followed by three online quantitative studies, using samples from diverse Chinese social media users. In Study 1 (N = 30), in-depth interview data were analyzed using grounded theory to establish the motivational structure of goal disclosure. In Study 2 (N = 180), we developed a parsimonious 20-item scale to measure UMGDSM. In Study 3 (N = 407), the reliability and validity of the multidimensional scale were established. In Study 4 (N = 412), we determined the nomological validity of the scale by documenting the relationship between the UMGDSM and goal attainment. As the first study to conceptualize and operationalize UMGDSM, this work establishes a foundation for understanding motivations behind goal disclosure behaviors on social media, uncovers the diverse effects of UMGDSM on goal attainment, and broadens the theoretical perspective on goal disclosure. These findings offer valuable insights for social media users and businesses in refining publicity and implementing data-driven, precision marketing strategies.