Nanotechnology facilitates numerous magnificent applications due to the desired shapes and size of the nanoparticles (NPs). However, restricted study of synthesis and characterization of rare earth metal make them more fascinating to choose for further research, lanthanum oxide nanoparticles (La2O3 NPs) is an excellent choice for research due to their fabulous applications in electronics, sensors, insulators, antimicrobial agents, biomedicines, and biocatalyst. Due to countless importance of La2O3 NPs, in literature its synthesis is described by several chemical, physical methods, and there are quite a few reports exploring plants as catalyst to achieve synthesis goals. In a green synthesis of La2O3 NPs using plants, the plant extract is used as a surfactant that encompasses the biomolecule leds the bio-reduction of lanthanum salt into the La2O3 NPs. This review enlightens the synthesis, characterization, and applications of the La2O3 NPs obtained using various plant extracts.