The rise of social media has transformed traditional marketing paradigms, offering unprecedented opportunities for audience targeting, content dissemination, and consumer engagement. This study investigates how marketing strategies have evolved in the digital era by analyzing the effectiveness of content formats, influencer tiers, and platform-specific dynamics. Using a multi-method approach, the research combines structured surveys, platform analytics, and experimental campaign tracking across Facebook, Instagram, Twitter/X, LinkedIn, TikTok, and YouTube. Key metrics include engagement rate, click-through rate, conversion rate, return on ad spend, audience growth, sentiment analysis, and user session behavior to assess the depth and quality of user interaction. The findings highlight the effectiveness of short-form video and the cost efficiency of micro-influencer campaigns, where platform fit and customization emerged as strong predictors of conversion. The results further indicate that success in digital marketing arises not from isolated tactics but from the strategic integration of content format, duration, and influencer selection. Employing multilevel modeling and negative binomial regression on a large-scale dataset, the study underscores the complexity of user behaviors in today’s digital environment and provides empirically grounded recommendations for optimizing campaign effectiveness.