The purpose of this diploma thesis is to provide a comprehensive overview of the new environmental policies that are regulated by international and regional bodies in an effort to support decarbonization. More precisely, a reference is made to the IMO’s Annex VI of MARPOL for the Prevention of Pollution from Ships and the EU’s efforts through the Fit for 55 package to reduce the carbon footprint across Europe by introducing tools in order to monitor, tax and trade emissions. However, the current research is mainly focused on the analysis of the FuelEU Maritime Regulation that sets carbon intensity limits on the vessels operating inside the European Economic Area. The research outlines the regulation’s structure, its objectives and the actions needed for achieving compliance. In addition, the strategies a shipowner can pursue are presented, since it remains unclear which approach—whether operational measures, retrofitting the existing fleet, or investing in new fuel-efficient vessels—will be the most effective for complying with the regulation. Moreover, the employment of alternative fuels, such us low carbon intensity fossil fuels, e-fuels, methanol, biofuels, ammonia, hydrogen are evaluated, along with the potential role of renewable energy sources that will possibly be used in the upcoming years. Lastly, a case study in a shipping company is conducted, outlining the implications of the FuelEU Maritime Regulation on the maritime sector, while considering all the stakeholders of the shipping industry.