Although loneliness is related to mobile phone addiction among college students, little is known about the mediating mechanisms underlying this association. On the basis of the Interaction of person-affect-cognition-execution model for addictive behaviors, self-verification theory, and previous results of empirical studies, the present study examined the mediating roles of boredom proneness and core self-evaluation in the relationship between loneliness and mobile phone addiction among college students. A sample of 1300 Chinese college students (mean age = 20.40 years, SD = 0.97) were recruited to complete a series of questionnaires measuring loneliness, boredom proneness, core self-evaluation, and mobile phone addiction. These results showed that loneliness was positively correlated with mobile phone addiction; boredom proneness and core self-evaluation partially mediated this relationship when they operate in a parallel fashion. The relationship between loneliness and mobile phone addiction was mediated totally by boredom proneness and core self-evaluation when they operate sequentially. These findings help us to better understand the relationship between loneliness and mobile phone addiction and provide implications for the prevention and intervention of mobile phone addiction.