Ocean warming and marine heatwaves (MHW) are expected to significantly affect marine species’ physiology, compromising species survival. Transgenerational plasticity (TGP) may provide a rapid mechanism for marine organisms to acclimate to warming; however, the degree of acclimation and whether it differs among genotypes is unknown. Here, we assess the TGP response of two genetically distinct families of the Sydney Rock Oyster, Saccostrea glomerata to elevated temperatures. Adults of each family were exposed to a control (24 °C) and warming (28 °C) temperature for ~8 weeks during reproductive conditioning. Following this, within-family crosses were made and percentage development, abnormality, shell length and LT50 of embryos after 48 hours were measured across temperatures ranging from 24 to 36 °C. Overall, embryos from parents exposed to warming conditions had greater development, lower abnormality, but were smaller in size, at warmer temperatures compared the those from parents exposed to control conditions. LT50s indicated that parental exposure to warming increased the tolerance of embryos from one family by 2 °C but did not change the LT50 of embryos from the other family. Our findings suggest that TGP rapidly protects S. glomerata embryos against warming, however, the extent of this protection may depend on genotype.