Internet Addiction (IA) and phubbing are prevalent, disruptive behaviours among university students. The aim of this study was to explore the relationship between IA and Phubbing with psychological variables (impulsiveness, self-esteem, and psychological distress), academic performance and self-perception of mathematical competence (SMC), as well as possible gender differences. Results showed (n = 715; Mean Age = 21.7) gender differences in lack of planning, emotional investment and somatisation and IA correlated positively with app addiction, mobile addiction, and psychopathology. A total of 26.3% of IA can be explained by a lack of self-control, time and performance management, mobile phone addiction, anxiety and psychological distress. Finally, 71% of students believe that the use of new technologies has worsened their SMC and this is correlated with impaired communication, obsession with mobile phones, IA (Total Phubbing Scale) and impulsiveness. Our results indicate the importance of taking into account psychological variables that affect the development of IA, phubbing, and SMC in the university population.