Background: Artificial intelligence-driven platforms increasingly mediate social interaction through hyperpersonalized content delivery, raising concerns about their effects on individualism and social cohesion. Despite growing recognition of AI's social impacts, systematic understanding of mechanisms through which algorithmic personalization promotes individualistic orientations and reconfigures traditional social structures remains limited. Objective: This study examined how AI technologies promote individualism and transform social fabric by investigating: (1) mechanisms through which AI personalization algorithms foster individualistic behaviors and worldviews; (2) effects of AI-mediated individualism on community participation, civic engagement, and social solidarity; and (3) differential impacts across demographic groups and cultural contexts. Methods: A cross-sectional mixed-methods study was conducted between March 2024 and January 2025 across five countries (USA, UK, Japan, South Korea, Uganda) representing varying individualism-collectivism orientations. Using stratified random sampling, 2,847 participants aged 18-65 years who regularly used AI-driven platforms completed structured questionnaires measuring AI usage intensity, platform diversity, personalization awareness, individualistic orientation (0-100 scale), social cohesion index, and demographic characteristics. Data analysis employed univariate descriptive statistics, bivariate analysis (chi-square tests, t-tests, ANOVA, correlation analysis), and multivariate modeling including binary logistic regression predicting high individualism and multinomial logistic regression predicting social cohesion levels, with interaction terms examining cultural context moderation effects. Results: Univariate analysis revealed significant cross-national variations in AI usage (M=24.3 hrs/week overall; range: 18.9-28.7), individualism scores (M=62.4; range: 52.1-71.8), and social cohesion (M=54.7; range: 48.2-64.3), with Western countries demonstrating higher AI usage and individualism but lower social cohesion (all p