Wearable technologies have become useful instruments in providing accurate and trustworthy information about individuals’ activities, especially for health-and-fitness related purposes. However, the constant and ubiquitous data practices of wearable devices bring challenges to users’ privacy and security. This study focused on smartwatches and investigated how users’ personalities, trust, and the usability of the device affected their privacy perceptions while using the wearable device. Our results indicated that users who demonstrated a high tendency towards neuroticism had more awareness about third-party data sharing after a wearable trial. Also, those high in personal trust were less concerned about privacy. In addition, we found that the usability of a device affected the users’ perceptions of data practices. As the first study of its kind, we provide several suggestions for designing privacy-enhancing wearable devices and for future research.