In recent years, omnichannel strategies have increased, which has changed consumer purchasing decisions process. With this, the purchase decision has changed the way consumers approach to make purchase decisions, which leads to the purchase process being reshaped. The approach has become more complex with other aspects to consider in current consumer purchasing decisions. Therefore, the purpose of this thesis has been to investigate how omnichannel strategies, which integrate online and offline shopping platforms, shape consumers' purchase decisions in Sweden's fast fashion industry for generation Z. The empirical results were obtained using a qualitative case study of 25 participants from Sweden through semi-structured interviews. The findings were then analysed and discussed with the presented literature to identify how consumers' purchase decisions in Sweden's fast fashion industry for generation Z have been shaped by omnichannel strategies, integrating online and offline shopping platforms. The conclusion of this thesis shows that it is complex to assume how omnichannel strategies, integrated by online and offline shopping platforms, shape generation Z purchase decisions in Sweden's fast fashion industry because the impact of these strategies is unique to each individual's shopping journey. This means that every purchase decision is personally individual and varies depending on the consumer's unique approach to purchasing in the complex and interconnected world of integrated omnichannel strategies, where the online and offline channels are seamlessly connected to provide a unified shopping experience.