Many attempts have been made for green synthesis of metal oxide nanoparticles; revealing the importance of plant extracts in reducing metal/ metal oxide precursor to nanoparticles and their applications in various scientific domains. Cajanus cajan (L.) Mill sp. (Pigeon pea), one of the pulses in human diet is legume plant, belonging to family Fabaceae or Papilionaceae. This plant has been reported to contain several phytochemicals like flavonoids glycosides, stilbenes. This article focus on applications of Cajanus cajan extract in fabrication of nanoparticles of various metals and metal oxides like silver, gold, titanium dioxide, zinc oxide. In respective research attempts, these nanoparticles were evaluated for one or more applications like anti-microbial activity and/or photocatalytic activity. Use of polar extract of Cajanus cajan indicated involvement of its polar phyto-compounds in reducing the metal source and stabilizing the nanoparticles.