This study investigates the effect of social media marketing on consumer buying behavior toward the 100 Plus soft drink brand. Rapid growth in social media has transformed how FMCG companies engage consumers, yet 100 Plus faces challenges in effectively targeting diverse audiences in Malaysia and Singapore. Using a quantitative research design, primary data were collected through a structured questionnaire distributed via Google Forms, yielding responses from 30 participants selected through systematic sampling. The survey measured brand awareness, engagement, content appeal, perception, brand loyalty, and buying behavior using a five-point Likert scale. Descriptive analysis revealed that social media marketing significantly enhances consumer perception of 100 Plus, increases brand loyalty, and positively influences purchase decisions. Findings also show strong engagement through contests, visuals, and user-generated content, though brand awareness and content relevance require improvement. Overall, the study concludes that strategic social media marketing plays a crucial role in shaping consumer behavior and strengthening brand loyalty.