Despite increasing scholarly interest in youth language practices, limited empirical research has examined the relationship between Filipino Gen Z slang usage and social belonging among senior high school students in Philippine educational settings. This quantitative descriptive-correlational study investigated the relationship between Filipino Gen Z slang usage and social belonging among senior high school students at Aklan Catholic College during the 2025–2026 academic year. A total of 100 Grade 11 & 12 students from various academic strands were selected through cluster sampling. Data were collected using a researcher-developed questionnaire consisting of two 4-point Likert scales measuring the frequency of Filipino Gen Z slang usage and students’ sense of social belonging. Descriptive statistics were used to summarize demographic characteristics and levels of slang usage and social belonging, while Spearman’s rank-order correlation determined the relationship between the variables. Findings revealed that students frequently used Filipino Gen Z slang and reported a relatively high sense of social belonging. Social media and peer interactions emerged as the primary sources of slang exposure. Furthermore, a significant moderate positive correlation was found between Filipino Gen Z slang usage and social belonging (rₛ = 0.464, p < .001), leading to the rejection of the null hypothesis. The findings support Communication Accommodation Theory, suggesting that the use of shared slang facilitates peer acceptance and strengthens group integration among Filipino adolescents. These results highlight the role of youth language practices in fostering inclusive school environments and provide implications for educators, counselors, and future research.