We present a search for light dark matter particles through their interactions with atomic electrons and nucleons, utilizing PandaX-4T data with an effective exposure of 1.04 tonne·year for ionization-only data and 1.20 tonne·year for paired data. Our analysis focuses on the energy range (efficiency >0.01) of approximately 0.33 to 3 keV for nuclear recoils and from 0.04 to 0.39 keV for electronic recoils. We establish the most stringent constraints on spin-independent dark matter-nucleon interactions within a mass range of 2.5-5.0 GeV/c^{2}, spin-dependent neutron-only interactions within 1.0-5.6 GeV/c^{2}, and spin-dependent proton-only interactions within 1.0-4.1 GeV/c^{2}. Their corresponding limits at 3 GeV/c^{2} are 1.1×10^{-43}, 8.4×10^{-40}, and 2.8×10^{-38} cm^{2}, respectively. Additionally, our results improve the upper limits on the dark matter-electron scattering cross section by a factor of 1.5 and 9.3 for heavy and light mediator scenarios, respectively, within 50 MeV/c^{2} to 10 GeV/c^{2}, compared with previous best results. The improved limits reach 1.5×10^{-41} and 5.6×10^{-37} cm^{2} at 200 MeV/c^{2} for the heavy and light mediators, respectively.