Colour plays a significant role in cinema as a visual tool that communicates emotion, meaning, and narrative intent. Rather than functioning only as an aesthetic element, colour operates as a form of visual language that influences audience perception and psychological response. This research paper examines how colour theory is applied in cinema to shape mood, convey character psychology, and support storytelling. The study draws upon theoretical perspectives from colour psychology and film studies, along with an analysis of historical developments in cinematic colour usage. The paper explores how filmmakers use specific colour palettes and contrasts to evoke emotional responses and guide audience interpretation. Case studies from selected films, including the works of Anurag Kashyap and Disney animated cinema, are used to demonstrate how colour functions as a narrative device across different cinematic contexts. In addition, the study considers the role of colour in movie poster design to highlight how visual marketing also relies on colour to communicate tone and genre. Through qualitative analysis of visual examples and existing literature, this research finds that colour consistently functions as a powerful storytelling tool that enhances emotional engagement and strengthens narrative meaning. The findings suggest that understanding colour as a visual language contributes to a deeper appreciation of cinema and its ability to influence how audiences experience and interpret films.