BACKGROUND: Social anxiety disorder (SAD) is a common but under-treated mental health condition. Internet-based cognitive behavioral therapy (iCBT) and virtual reality exposure therapy (VRET) are effective treatment approaches for SAD. However, few studies have integrated both, particularly in Chinese communities. This study examines the effectiveness of a 14-week iCBT program that includes VRET, called "Ease Anxiety in Social Event Online" (Ease Online), among Hong Kong adults with SAD. METHOD: 329 Hong Kong Chinese adults with SAD were randomized into web-based iCBT with VRET (n = 117), app-based iCBT with VRET (n = 111), or waitlist control (WLC) (n = 101) groups. The mean age was 30.49 years old (SD = 9.34), with 36 % male and 64 % female. Assessments were administered at pre-test, post-test, and 3- and 6-month follow-ups. The primary outcome measure was the Social Phobia Inventory (SPIN). Data were analysed by using linear regression and mixed effects models. RESULTS: Both treatment groups were superior to WLC group on both the primary and secondary outcome measures. The effects were comparable between the two iCBT formats. Improvements were maintained at 3-month and 6-month follow-ups. The rate of reliable improvement based on the SPIN was 34 % and 40 % in the web-based and app-based iCBT groups, respectively, compared to 11 % in the WLC group; and 15 % and 23 % who meet the criteria for remission of social anxiety, compared to 3 % in the WLC group. CONCLUSIONS: Both web- and app-based iCBT with VRET are effective for Hong Kong Chinese adults with SAD. The EASE Online iCBT programme is an effective treatment approach for Hong Kong Chinese with SAD.