This bachelor’s thesis, titled “The Influence of Corporate Social Responsibility on Customer Loyalty and Brand Perception,” examines how corporate social responsibility (CSR) impacts customer loyalty and brand perception. The study focuses on online promotion channels, particularly Instagram, as a key platform for communicating CSR activities of an athletic store managed by the author. The research analyzes various CSR initiatives, including environmental sustainability, community engagement, and ethical labor practices, and evaluates how these efforts influence brand reputation, customer satisfaction, and loyalty. A mixed-methods approach was applied, combining quantitative surveys with customers and qualitative interviews with employees to gain a comprehensive understanding of stakeholder perceptions. The findings indicate that CSR activities significantly enhance brand reputation and equity, leading to increased customer satisfaction and loyalty. Customers are more likely to support brands that demonstrate genuine commitment to social and environmental causes. Additionally, CSR positively affects employee satisfaction, engagement, and advocacy, reinforcing the importance of aligning CSR initiatives with organizational values. The study also explores psychological factors such as brand trust, emotional attachment, and moral satisfaction that explain how CSR influences consumer behavior. Case studies of companies like Patagonia, TOMS, and Ben & Jerry’s highlight effective CSR implementation. The thesis concludes with practical recommendations for integrating CSR into marketing strategies and emphasizes the importance of authentic and transparent communication to achieve sustainable competitive advantage.