Aim: In this study, the effects of the addiction level of smartphone use in university students on the range of motion and proprioception of the dominant hand, wrist range of motion (ROM), and thumb ROM were investigated. Material and Methods: Wrist and thumb ROMs were measured with a manual goniometer with a sensitivity of 1 degree, and hand grip strength was measured with a hand grip dynamometer in a total of 100 volunteer university students with a mean age of 18-25. Smartphone Addiction Scale-Short Form (SAS-SF) and Patient Rated Wrist and Hand Evaluation (PRWHE) questionnaire were applied to the students. Statistical analyzes were made using the SPSS 25 program. Results: The students’ usage time of smartphones and addiction levels do not affect the hand grip strength; the increase in smartphone addiction statistically correlates with the right thumb flexion (0.016) and abduction ROMs (0.015), statistically correlated with increased pain level in daily life and statistically correlated with the decrease of the wrist radial deviation ROM (0.009). As the duration of smartphone use increases, the error rate in right thumb abduction proprioception statistically increases (0.027). In addition, we determined the statistically correlations in both thumb flexion and abduction movements. Conclusion: We determined that the excessive usage of smartphones affects the ROM of thumb flexion and abduction, the ROM of wrist radial deviation, and the proprioception of thumb abduction, and it does not affect the hand grip strength. The findings of our research will be a source for future studies.