Blood flukes of the genus Schistosoma are the causative agents of human schistosomiasis, a debilitating disease that afflicts over 200 million people worldwide. Praziquantel is the drug of choice but concerns over praziquantel resistance have renewed interest in the search for alternative drug therapies. Carvacrol, a naturally occurring monoterpene phenol and food additive, has been shown high medicinal importance, including antimicrobials activities. The aim of this study was to evaluate in vitro effect of carvacryl acetate, a derivative of carvacrol, on Schistosoma mansoni adult worms. We demonstrated that carvacryl acetate at 6.25 μg/mL has antischistosomal activity, affecting parasite motility and viability. Additionally, confocal laser scanning microscopy pictures revealed morphological alterations on the tegumental surface of worms, where some tubercles appeared to be swollen with numerous small blebs emerging from the tegument around the tubercles. Furthermore, experiments performed using carvacryl acetate at sub-lethal concentrations (ranging from 1.562 to 6.25 μg/mL) showed an inhibitory effect on the daily egg output of paired adult worms. Thus, carvacryl acetate is toxic at high doses, while at sub-lethal doses, it significantly interferes with the reproductive fitness of S. mansoni adult worms. Due to its safety and wide use in the industry, carvacryl acetate is a promising natural product-derived compound and it may represent a step forward in the search for novel anthelmintic agents, at a time when there is an urgent need for novel drugs.