The present work investigates the mechanical strengths retention and prediction of maximum service life of sets of laminated composites by analyzing their diffusion coefficients and activation energies, using Fick’s law and Arrhenius principle. Jute fiber woven mat reinforced epoxy laminated composites (JFMRLCs) were prepared by simple hand lay-up and compression molding methods. The layering patterns of 0º balanced laminate of [0º/0º/0º/0º/0º], 30º angle-ply laminate of [0º/+30º/0º/-30º/0º] and 45° angle-ply laminate of [0°/+45°/0°/-45°/0°] were used to prepare the composite samples, according to classical laminated plate theory (CLPT). The composites were immersed in water at different periods of 10, 20, 30 and 40 days aging. The effects of the various periods of aging on their mechanical properties were studied. The results showed that the weights of the composite samples increased by increasing the aging periods. The mechanical properties of aged (wet) composites were compared with the unaged (dry) counterparts to predict their strengths retention. The composite with 45° layering pattern exhibited the maximum strength retention. Also, the same composite sample with layering pattern of 45° produced the maximum activation energy, based on Arrhenius principle. The tensile fractured surfaces were analyzed to investigate into their fiber-matrix interfacial bonds through images obtained from scanning electron microscopy (SEM). Summarily, it was evident that optimum JFMRLCs with layering pattern of 45° exhibited best mechanical properties. Hence, they can act as suitable, sustainable, low cost and environmentally friendly composite materials for structural marine and other related engineering applications.