610 Despite the rapid expansion of social media marketing in emerging markets, literature has substantially neglected the Bottom of the Pyramid consumer segment in MENA markets. In Egypt, nearly 30% of the population resides below the national poverty line (CAPMAS,2023). Furthermore, over 60% of the population ranging from low-to-middle income bracket. (International Monetary Fund, 2024). The purpose of this study is to examine the effect of Social Media Marketing activities on purchase intention among Bottom of the Pyramid consumers in Egypt’s FMCG sector, to test whether sustainability perception moderates this relationship. Addressing this gap, we developed a conceptual framework measuring the effects of social media marketing activities on Bottom of the Pyramid customers’ intention to purchase with the moderating role of sustainability perception. An online survey with 270 valid respondents was conducted, the data being analyzed using Partial 1east squares structural equation modeling (PLS-SEM). The results showed that Social Media Marketing activities have a significant positive effect on purchase intention (β = 0.962, p < .001, R² = 0.928). Although sustainability exerted small but significant direct effect on purchase intention (β = 0.141, p = 0.001), it did not moderate the relationship between Social Media Marketing activities and purchase intention. The study challenges the assumption that sustainability perception functions as a boundary condition in low-income consumer contexts and extends the Social Media Marketing activities framework to Bottom of the Pyramid consumers. The study also highlights the actionable insight for FMCG marketers: when targeting low-income Egyptian consumers on social media, prioritize entertaining, informative, and e-WOM driven content. https://jbrmr.com/details&cid=610 https://jbrmr.com/cdn/article_file/ROGE-JBRMR-2026-3024-PRV-Sara-Mohamed-Abdelaziz-El-Menawy.pdf Volume 21 Issue 01 59 2026-10-01 2026-09-29 no 0000-00-00 0000-00-00 0000-00-00 0000-00-00 Social Media Marketing Activities Purchase Intention Bottom-of-the-Pyramid Consumers Sustainability Perception FMCG Sector Consumer Behaviour Egypt. none 16 3 0 Sara Mohamed Abdelaziz El-Menawy Future University in Egypt Noha Magdy Kamel El-Sharawy Future University in Egypt