This study examined patterns of Generative AI use and their influence on the critical thinking skills and academic achievement of Gen Z learners using a descriptive-correlational design. Data were collected from 62 Grade 11 and 12 HUMSS students of Lyceum of Camalaniugan through a structured questionnaire and analyzed using descriptive and inferential statistics at a 0.05 significance level. Results showed that most respondents, aged 16–18 and predominantly male, frequently used smartphones and relied on moderate internet connectivity, with ChatGPT as the most commonly used AI tool for academic purposes at a moderate level of dependency. Overall, Generative AI use and its influence on critical thinking were both moderate. No significant differences in AI use were found by sex or grade level, except for age, while bandwidth significantly affected critical thinking. Academic achievement had negligible relationships with AI use, though dependency showed a significant negative relationship. Findings suggest that while Generative AI is useful, it requires guided and responsible use.