The basis of this master's thesis is the phenomenon of influencer marketing. In addition to defining this term, the paper clarifies the importance of digital marketing with special reference to social networks, which are a key factor in the cooperation between companies and influencers. A comparison of the digital marketing with the traditional form of marketing is made, and then the main advantages and disadvantages of influencer marketing are described. The key steps that need to be taken in order for both sides of the partnership to be satisfied and for the cooperation to result in the best possible result are listed. Then, two case studies were presented, in which two campaigns were analyzed in detail, one of which ended with a gold award for the best advertisement, and the other resulted in big damage felt by both the brand and the influencer. The practical part of the paper is devoted to research in which primary data, collected through online surveys, were used. The goal of the research was to discover the opinions and attitudes of consumers about influencers and the strength of their influence on their shopping habits. 165 people participated in the research. The respondents belong to different target groups, but they all use social networks for at least an hour a day. As many as 110 (67.1%) respondents follow at least one influencer on social networks, which shows the importance and strength of this new but very popular phenomenon.