Abstract Objectives The purpose of this study was to assess and compare the efficacy of different electronic devices (VR headsets and tablet devices) supported mindfulness exercises. Contrary to previous studies, we compared the technologies not only regarding psychological but also physiological parameters. Additionally, we assessed time perception as an indicator of flow state, which can increase therapeutic adherence. Method Fifty volunteers (26 females and 24 males) aged 19–28 years (M = 23, SD = 1.93 years) participated in our cross-over trial. A 20-min mindfulness program (Guided Meditation VR™) was shown on both a VR headset and a tablet device, with a 1-week interval in randomized order. Psychological parameters and time perception were assessed through surveys, and an Empatica E4 wristband collected physiological data (heart rate, body temperature, electrodermal activity). Results Both VR- and tablet-based mindfulness programs reduced stress, as reflected by improvements in both anxiety (a 7.06-point reduction in STAI-Y score, p < 0.001) and in-session physiological parameters (a 4.82 bpm reduction in HR, p < 0.001; 1.11 °C increase in body temperature, p < 0.001), without significant differences between the two devices. However, participants perceived the intervention as shorter than its actual time only in the VR condition (VR: 26 shorter, 9 longer out of 47, p = 0.006; tablet: 20 shorter, 14 longer out of 47, p = 0.39). Conclusions While affirming the efficacy of electronic device-supported mindfulness in stress reduction, our study suggests no significant disparity between VR and tablet-supported exercises. Our findings also suggest that participants in the VR session perceived the intervention as shorter than its actual duration. Preregistration This study is not preregistered.