The rapid proliferation of social media platforms has changed the landscape of marketing and brand engagement. This study examines the profound impact of social media marketing on brand preference among centennials, the generation born between 1997 and 2012, living in Chennai, India. As digital natives, centennials have grown up with social media as an integral part of their lives, making them an interesting demographic to study. This study uses a comprehensive questionnaire survey as the primary data collection method to assess the dynamics between social media use, brand engagement, and purchase behavior. The questionnaire addresses frequency of social media use, platform preferences, factors influencing brand preferences, and the role of trust and authenticity in Centennials' interactions with brands on social media. In addition, this study examines the extent to which Centennials trust brand content on social media, how they respond to unsatisfactory brand interactions and the impact of interactive brand campaigns on their perceptions. In addition, the study examines whether centennials make online purchases that are influenced by social media content and evaluates the effectiveness of various social media platforms for brand marketing. The results of this study are expected to provide valuable insights into the strategies brands can employ to effectively target and influence Centennials through social media marketing. Understanding the preferences and behaviors of this generation in the context of Chennai can help companies tailor their marketing efforts to leverage the potential of social media platforms to drive brand preference and ultimately increase sales.