A mixer with a filtering function and a method for linearization of the mixer are provided. The mixer includes at least one amplifier, a transconductance device and a feedback network. The at least one amplifier is configured to output a filtered voltage signal according to an input voltage signal. The transconductance device is coupled to the at least one amplifier, and is configured to generate a filtered current signal according to the filtered voltage signal. The feedback network is coupled between any output terminal among at least one output terminal of the transconductance device and an input terminal of the at least one amplifier. More particularly, the mixer is configured to output a modulated signal according to the filtered current signal.