Icing deteriorates the performance of wind turbine rotors by changing the blade airfoils’ shapes. It decreases the lift, increases the drag, and subsequently causes power production losses and load increase on turbines’ structures. In the present study, the effects of atmospheric icing on the performance of a controlled large-scale wind turbine is estimated through simulations. To achieve the target, the MS (Mustafa Sahin) Bladed Wind Turbine Simulation Model is used for the analyses of the National Renewable Energy Laboratory (NREL) 5 MW turbine with and without iced blades. Icing modeling is realized based on its main characteristics and its effects on blade aerodynamics. Turbine performance estimations are carried out at various uniform wind speeds between cut-in and cut-out wind speeds and are presented in terms of various turbine parameters such as power, thrust force, blade pitch angle, and rotor speed. Simulation evaluations show that even a light ice accretion along the blades varies the turbine characteristics and dynamics, changes the cut-in and rated wind speeds, and affects the aforementioned turbine parameters differently in the below and above rated regions.