Floating offshore wind energy has great potential (which constitutes almost 80% of total offshore wind energy) to meet electricity demand of the world at the same time to reach net-zero emission goal by 2050. Floating offshore wind turbines (FOWT) are able to achieve highest capacity factor since local effects of the offshore terrains are lesser. Thus, it receives stronger and more stable wind. On the other hand, combined hydrodynamic and aerodynamic forces with 6 degrees of freedom (DoF) bring unsteadiness and therefore, challenges on FOWT design. Furthermore, significant rotational motions, particularly pitch motion, lead the turbine to transient state which can not be simulated through conventional numerical tools. Therefore, to understand the dynamics of the FOWT, it is necessary to conduct experimental studies to obtain results by considering all the parameters. The main aim of the thesis is to investigate the dynamic response of the FOWT under the extreme wind and wave conditions. A 1/40 Froude-scaled version of the Northel POYRA P36/300 mounted on the spar-type floating platform was developed by colleagues as a part of TUBITAK (217M451) project. In this thesis, experimental studies were carried out in the wave flume with a wind nozzle in the hydraulic laboratory of IZTECH Civil Engineering Department. Atmospheric boundary layer (ABL) was scaled, and instruments of the experiment were calibrated to characterize wind nozzle and wave maker, which are vital to obtaining reliable results. The wind nozzle was designed based on experimental data to reproduce correct Froude-scaled ABL.