A method and an image processing device for image color enhancement are proposed. The method includes the following steps. An input image having input pixels is received, where each of the input pixels includes a luminance component and two chrominance components. A saturation gain of each of the input pixels is determined according to the chrominance components thereof. The chrominance components of each of the input pixels are adjusted according to the saturation gain thereof so as to generate enhanced pixels. An enhanced image is outputted according to the enhanced pixels.