A system and method for detecting ice on a rotor blade of a wind turbine are disclosed. In one embodiment, the method may include releasing a pitch brake of a pitch adjustment mechanism associated with the rotor blade, controlling the pitch adjustment mechanism so as to maintain the rotor blade at a fixed pitch angle, monitoring a pitch-related parameter of the wind turbine while the rotor blade is maintained at the fixed pitch angle, and analyzing the monitored pitch-related parameter to determine whether ice is present on the rotor blade.