The research in the area of spintronics is gaining momentum due to the promise spintronics based devices have shown. Since spin degree of freedom of an electron is used to store and process information, spintronics can provide numerous advantages over conventional electronics by providing new functionalities. In this article, we study spin relaxation in graphene nanoribbons (GNR) of armchair type by employing semiclassical Monte Carlo approach. D׳yakonov-Perel׳ relaxation due to structural inversion asymmetry (Rashba spin–orbit coupling) and Elliott–Yafet (EY) relaxation cause spin dephasing in armchair graphene nanoribbons. We investigate spin relaxation in α-,β- and γ-armchair GNR with varying width and temperature.