Despite the burgeoning adoption of informal learning in people's daily lives, the actual effects of informal learning activities, especially technology-related informal learning activities, are much less reported than those of formal learning. Furthermore, there is a notable lack of research on the effects of technology-related informal mathematics learning activities (TRLA). This study aims to propose and validate a new model which illustrates the effects of TRLA on four constructs: mathematics self-efficacy (MSE), mathematics interest (MI), self-regulation in mathematics learning (SR), and teacher-student relationship (TSR). Adopting a quantitative cross-sectional survey approach, 460 students were investigated. The data were analyzed employing two-step structural equation modeling. Our findings demonstrate the direct effects of TRLA on MI and SR as well as the indirect effects on MI, MSE, and TSR. This study advances the understanding of technology-enhanced informal learning, which is an emerging perspective of technology-enhanced learning.