Background: Smartphone addiction has emerged as a significant social problem. Numerous studies have indicated the association between smartphone use and discomfort in the musculoskeletal system of the upper extremities. Objects: This cross-sectional survey aimed to compare the characteristics of musculoskeletal pain in the neck, trunk, and upper limbs between individuals with smartphone addiction and those without addiction. Methods: We collected a total of 326 healthy individuals’ data from China and Korea who had owned and used smartphones for more than 5 years between 20–50s through an online questionnaire consisting of 84 questions in four major sections. The first part contained basic information on the participant's personal characteristics and smartphones. The second part contained questions about smartphone use and posture. The third part was the smartphone addiction. The fourth part was to investigate musculoskeletal pain in various upper body parts. Results: Smartphone addiction has a weak negative correlation with age (r = –0.20, p < 0.01) and a weak positive correlation with the hours of smartphone use (r = 0.376, p < 0.01). Frequent musculoskeletal pain symptoms related to smartphone use were observed in the neck, shoulder, lower back, and wrists. The hours of smartphone use was slightly positively associated with the prevalence of musculoskeletal pain in the shoulder (r = 0.162, p < 0.05) and lower back (r = 0.125, p < 0.05). The prevalence of musculoskeletal pain in the neck (χ2 = 3.993, p < 0.05), shoulder (χ2 = 6.465, p < 0.05), and wrist (χ2 = 4.645, p < 0.05) was significantly higher among females than males. Conclusion: The results suggest that smartphone addiction should be recognized as a dual concern encompassing both physical health and psychosocial aspects. Furthermore, healthcare professionals, including physicians and physical therapists, should consider clients' smartphone usage patterns when assessing and treating with musculoskeletal pain.