A Social Media Influencer (SMI) is a new independent third party that uses social media to shape audience attitudes. SMIs are present on most digital media platforms such as Facebook, Instagram, Twitter and YouTube, and build their sphere of influence by sharing their experiences on a wide range of specific topics such as fitness, fashion, beauty, DIY, vacation, entertainment, etc. with their followers. While making these posts, SMI creates a desire in social media users who are interested in those topics to follow influencers with high influence. This is because similar topics are also of interest to social media users and they feel SMI as a reflection of themselves. Therefore, every behavior of the influencer attracts more attention. This situation makes the job of marketers and brands easier. Because instead of their efforts to reach the target audience by developing many strategies, there is the SMI who brings together potential buyers who have formed their own target audience. In addition, reaching SMIs for advertising deals is less costly than reaching classic influencers. The purpose of this study is to develop and validate a scale that can measure the effect of SMIs' attitudes and behaviors on consumer purchase intention. Accordingly, the population of the study consisted of social media users who follow at least one SMI. Questionnaire method was used as a data collection tool in the research. While creating the scale items, expressions and phrases obtained from short interviews with consumers who use social media and follow at least one SMI were utilized in addition to the relevant domestic and foreign literature. Within the scope of the research, 821 questionnaires were accepted as valid and evaluated. As a result of the Structural Equation Model (SEM) application, it was determined that there is a significant effect of SMI on the effect of purchase intention.