Self-stigma is a common experience for people with substance use disorders (SUDs). Understanding factors associated with self-stigma may aid in intervention development. This study investigated the reciprocal relationship between three types of problematic use of the internet [PUI; i.e. problematic use of social media (PUSM), problematic smartphone use (PSPU), and problematic gaming (PG)] and self-stigma among people with SUDs. This longitudinal study involved five waves of a survey given to individuals with SUDs in Taiwan. A total of 319 participants (85% male), with a mean age of 42.2 years (SD = 8.9), were recruited. The Smartphone Application-Based Addiction Scale, Bergen Social Media Addiction Scale, Internet Gaming Disorder-Short Form, and Self-Stigma Scale-Short Form were used. No significant associations between PUI and self-stigma were found in early waves (i.e., Waves 1 and 2). The earliest significant finding was identified between Wave 2 PSPU (smartphone) and Wave 3 self-stigma. Additionally, Wave 3 PSPU (smartphone) and PG (gaming) were associated with Wave 4 self-stigma, and Wave 4 PSPU (smartphone), PG (gaming), and PUSM (social media) were associated with Wave 5 self-stigma. Therefore, all three types of PUI (internet) may elevate self-stigma at different time points for individuals with SUDs. However, the reciprocal effects between self-stigma and PUI (internet) only occurred in PUSM (social media) at a later stage (i.e., from Wave 4 to Wave 5). In conclusion, people with SUDs who have PUI (internet) are at increased likelihood of developing more self-stigma, which may then increase subsequent PUSM (social media), forming a vicious cycle.