This study explored undergraduates’ perspectives regarding information privacy on social media (Facebook and Instagram) to understand their disposition to privacy, online privacy concerns, and trust and risk beliefs. Moreover, a causal relationship model was established to assess the undergraduates’ information privacy concerns regarding social media platforms. A self-developed questionnaire survey was conducted with 374 undergraduates, with a response rate of 93.5%. Data collected were analyzed using item analysis, factor analysis, and a structural equation model. The results revealed the following: (1) Currently, the information privacy concerns of undergraduates regarding social media websites are at the upper-middle level, with their disposition to privacy being at the upper-middle level and their online privacy concerns being at a considerably high level. Moreover, their trust beliefs are moderate, whereas their risk beliefs are at the upper-middle level. (2) Disposition to privacy, online privacy concerns, and risk beliefs positively influence the undergraduates’ social media website information privacy concerns. (3) A causal relationship model was established to explain the relationship between the aforementioned factors and undergraduates’ social media website information privacy concerns. The study results provide insights into and can help predict undergraduates’ concerns regarding information privacy on social media websites.