Consumer buying behaviour has rapidly evolved in response to ongoing shifts in psychology, technology, and societal structures. Understanding these intertwined drivers is critical for marketers, researchers, and businesses seeking to engage diverse consumer segments across digital and traditional markets. Psychologically, consumers are influenced by motivation, perception, memory, and attitudes, which collectively guide decision-making and shape preferences. Emotional triggers, cognitive biases, and personal values further affect how individuals interpret marketing messages, making personalization a key determinant of purchase intention. This shift has been intensified by technological developments through algorithmic recommendations, targeted advertising, and user-centered e-commerce design. With big data analytics, real-time behavioral tracking, artificial intelligence can now help brands better forecast buying patterns than at any other time in history. These instruments shall improve convenience, shape loyalty, and create tailored experiences online which would foster impulse buying. Most importantly, friction in the purchase journey has gone down due to mobile commerce and optimized user interfaces, leading to more consumer dependence on automated suggestions and platform-based trust cues. Societally, factors such as family influence, peer behaviour, and socio-economic trends continue to mould spending habits. Globalization and evolving lifestyles have accelerated cultural convergence, promoting cross-border consumption behaviour. Social media platforms have emerged as dominant cultural ecosystems, driving trends through influencer endorsements, viral content, and online reviews. Digital communities offer social proof, validating purchasing decisions and amplifying brand credibility. Cultural trends, including sustainability awareness and ethical consumerism, also reshape preferences, motivating consumers to favour brands aligned with their values. This paper examines how these psychological, technological, and societal drivers intersect to shape modern consumer behaviour, offering insights into the mechanisms behind social media influence and cultural trend adoption. Findings indicate that digital environments have intensified the impact of psychological triggers while simultaneously redefining social norms. The research further highlights the implications for marketing strategies and suggests that future consumer behaviour will be increasingly shaped by immersive technologies and evolving cultural narratives. Ultimately, a deeper understanding of these drivers can enable organizations to design more ethical, efficient, and culturally responsive marketing practices.