Confinement effects may trigger certain non-trivial characteristics of droplet evaporation, which may incur far-reaching implications in practical scenarios. In effect, the vapor mediated interactions in a confined droplet may alter its intrinsic evaporation characteristics altogether, primarily as a consequence of significant increase in droplet lifetime due to enriched accumulation of the vapor field in the vicinity. Here, we derive a universal scaling law for the evaporation lifetime of a geometrically confined sessile droplet, appropriate to a wide gamut of droplet-substrate combinations. With asymptotic convergence to the classical picture in case of an unconfined droplet, the validity of our scaling law for droplet lifetime is comprehensively tested and benchmarked against a wide range of experimental data sets. These findings may turn out to be of profound importance in several emerging applications including micro-scale combustion and droplet based microfluidic technology. © 2018 Elsevier B.V.