Family functioning (FF) is associated with patterns of adults’ close relationship attachment, which works differently in western and non-western societies. In this study, the relationship between FF and attachment (A), as well as the difference in relationship between FF and A across western and non-western societies were examined. A total of 600 young adults (294 males, 306 females) were recruited from western and non-western societies through the SurveyCircle and social media and communication applications. The data was analyzed using PLS-SEM and multigroup analysis, and the results showed that in western and non-western societies, family adaptability and cohesion were significantly associated with anxiety, close, and depend attachments. Unexpectedly, higher family adaptability was associated with higher anxiety attachment. The associations among family adaptability and cohesion with anxiety, close, and depend attachments showed that the strengths of the relationships are significantly different in western and non-western societies, except for the association between family cohesion and anxiety. Based on these results, the cultural differences in terms of FF and young adults’ close relationship attachment were presented for future research, family therapy, and the society.