YouTube has become an important part of marketing activities today. Due to its potential to influence consumers' purchasing decisions, many brands promote and advertise their products and services on YouTube. However, the extent to which YouTube ads actually influence consumers' purchase decisions has become an important question for brands. In this study, the extent to which YouTube ads create brand awareness in consumers, the effect of this awareness on consumers' purchase intention, and the mediating role of brand preference in this effect are examined. Creating brand awareness alone is not enough to influence consumers' purchase behavior. In other words, the fact that consumers know a brand does not automatically mean that they will buy that brand. At this point, brand preference gains importance. Consumers consider factors such as brand quality, price and usefulness when choosing between brands. In the study, the survey technique, one of the quantitative analysis methods, was preferred and a total of 394 participants responded. The data obtained were analyzed with the SPSS 25 program and the research findings showed that as brand awareness increases, consumers' purchase intention also increases. In other words, when consumers see an advertisement of a brand and remember the brand, their intention to purchase the products or services of this brand increases. In addition, the results of the study showed that brand preference partially mediates the effect of brand awareness on purchase intention in a market where consumers have to choose between many different brands.