This paper introduces boss phubbing (phone snubbing), defined as an employee's perception that his/her immediate supervisor is distracted by his/her smartphone while in their presence, and studies its relationship with employee performance. Despite the importance of supervisor-subordinate interactions and the ubiquitous nature of smartphones, research is yet to investigate how smartphones impact important employee outcomes. Three theories are used to undergird the proposed model of relationships between boss phubbing, supervisory trust, job satisfaction, and performance: Reciprocated Social Exchange theory, Expectancy Violations theory, and Social Presence theory. A sequential mediation model was used to examine the relationships between boss phubbing and employee job performance. Two studies of US adults working in a range of industries (n=156, n=181) reveal that boss phubbing has a negative association with employee's job performance through supervisory trust and job satisfaction. Theoretical and practical implications and future research directions are also discussed.