The effect of ICT use on students’ academic achievement continues to be debated. While positive, negative, and non-significant linear relationships have been reported in the literature, few studies have examined the non-linear relationship between ICT use and academic achievement. Guided by the Opportunity-Propensity framework, this study addressed this gap by examining the non-linear relationships between four types of ICT use and students’ academic achievement. A two-level multiple indicators multiple causes model was conducted using Mplus version 8.0 on a representative sample of 15-year-old Hong Kong secondary students (N = 6,037, mean age = 15.73 years, 48.9% girls) from 152 schools. The results showed a linear, negative link between ICT use at school and ∩-shape links between ICT use for outside-of-school learning (with the peak at the 50 percentile), ICT use for leisure (with the peak at the 80 percentile), and using ICT as a topic in social interactions (with the peak at the 1 percentile) and their academic achievement. These findings suggest that stakeholders should always take caution when promoting ICT use at school and ensure that its use does not interfere with students’ learning activities outside of school. Copyright © 2022 Elsevier.