A method for performing phase shift control in an electronic device and an associated apparatus are provided, where the method includes: obtaining a set of clock signals corresponding to a set of phases; and controlling a phase shift of an output signal of an oscillator by selectively mixing the set of clock signals into the oscillator according to a set of digital control signals, wherein the phase shift corresponds to the set of digital control signals, and the set of digital control signals carries a set of digital weightings for selectively mixing the set of clock signals. More particularly, the method may include: selectively mixing the set of clock signals into a specific stage of a plurality of stages of the oscillator according to the set of digital control signals.