According to the common-sense model, illness perceptions influence one’s cognitive, affective, and behavioral responses to the corresponding illness. However, there is a lack of validated assessment tool for illness perceptions of either gambling disorder (GD) or Internet gaming disorder (IGD). This research project aims to address this gap by adapting of the Revised Illness Perception Questionnaire (IPQ-R) for GD and IGD and examining its psychometric properties in both cases. Two anonymous surveys were conducted: the GD questionnaire was applied to 690 university students (M_age=20), while a random sample of 1051 adults (M_age=40) was recruited for evaluating the IGD questionnaire. Confirmatory factor analysis results supported the original 7-factor model (i.e., timeline-chronic, timeline-cyclical, personal control, treatment control, illness-consequences, illness-coherence, and emotional representations) in IPQ-R for GD, but only 6-factor model (i.e., removal of timeline-chronic factor) for IGD. Despite this difference, both questionnaires and their subscales showed satisfactory internal consistencies. Their criterion-related validity was supported by the significant correlations between the subscales (including illness-consequences and illness-coherence) and stigma toward people with these addictions. We also found that gamblers/gamers had higher scores on illness coherence and lower scores on illness consequences than non-gamblers/gamers. Our results have given empirical support for using IPQ-R to measure illness perceptions of both GD and IGD. These tools are useful for not only testing the effects of various illness perceptions on individuals’ responses (help-seeking behaviors) to GD and IGD but also evaluating preventive programs of these two behavioral addictions.