Technology has revolutionised everyday existence. Information and Communication Technology (ICT) is essential to society, employment, and education. Improved microelectronics has facilitated the proliferation of inexpensive portable devices such as smartphones. This study, therefore, investigated whether senior secondary school students' nomophobia and smartphone addiction are linked to math anxiety. Two research hypotheses were tested and the study was guided by social cognitive theory. This study employed a descriptive survey research methodology and primary data were collected from 397 students in Ikorodu, Lagos, Nigeria with the use of the Nomophobia Questionnaire (NMP-Q, α=0.89), the Smartphone Addiction Scale Short Version (SAS-SV, α=0.82), and the Mathematics Anxiety Scale (MAS, α=0.81) developed by Yildirim and Correia (2015), Kwon et al. (2013), and Ablian and Parangat (2022) respectively. The data gathered were subjected to analysis using frequency counts, Pearson correlation, and regression analysis at 0.05 significance level. This analysis was conducted using SPSS software, specifically version 23.0. The research revealed a significant association between nomophobia and smartphone addiction among the students. Additionally, the severity of nomophobia and smartphone addiction emerged as significant predictors of mathematics anxiety among high schools in Lagos. Consequently, this investigation proposes that educational authorities in Lagos State should consider implementing a ban on mobile phone usage within secondary schools as a means to mitigate these behavioural addictions among adolescents. Additionally, stakeholders within the education sector, including parents, can contribute to the prevention of these addictions by advising students about the perils of smartphone addiction, fostering ethical social interactions that cultivate trust in the family unit, and imposing restrictions on their children's smartphone usage and associated expenses.