This study analyzed the performance, antioxidant status, hepatopancreatic lipoperoxidation, and proximate composition of Macrobrachium rosenbergii juveniles fed diets supplemented with clove basil (Ocimum gratissimum) essential oil (EO-OG). A total of 360 M. rosenbergii (initial weight 0.028 g ± 0.004) were randomly divided into four experimental groups with six replications each (n = 6). The prawns were fed diets with different EO-OG inclusion levels: 0.0, 1.0, 2.0, and 3.0 g kg⁻¹ EO-OG. After a 42-day feeding trial, dietary EO-OG showed no significant effect on prawn performance or carcass proximate composition, except on final antenna length. Prawns fed 3.0 g kg⁻¹ EO-OG displayed a 1.2- to 1.3-fold longer final antenna length than prawns from all other experimental groups. Likewise, prawns fed 3.0 g kg⁻¹ EO-OG presented a 2.6- to 3.2-fold higher catalase activity than prawns from all other experimental groups. Prawns fed EO-OG, regardless of the inclusion level, showed a 1.6- to 1.7-fold decreased hepatopancreatic lipoperoxidation compared to the control group. Therefore, EO-OG has been demonstrated to be a potential management tool as a non-nutritional dietary immunostimulant and animal welfare promoter for freshwater prawn farming, without affecting animal performance. This study recommends the dietary inclusion level of 3.0 g kg⁻¹ EO-OG for M. rosenbergii juveniles.