Objectives <p>This study evaluated the mechanical and surface characteristics of the transition zone of multilayered translucent zirconia (TZ) after aging and analyzed the correlation between the 4-point bending flexural strength (4PBFS) and biaxial flexural strength (BFS) in each zone.</p> Methods <p>Traditional (3Y-TZP of LT; L, 4Y-TZP of MT; M) and multilayered TZ (5Y-TZP of MT Multi; T, 3Y/5Y-TZP of Prime; P, 4Y/5Y-TZP of Prime esthetic; E) IPS E.max ZirCAD blocks were used to fabricate 525 disk-shaped and 300 bar-shaped specimens. Specimens were separated into three groups, aged in an autoclave at 134 °C under 0.2 MPa for 0 h, 5 h, and 10 h. The mechanical and surface characteristics of the transition zone in multilayered TZ were analyzed, following statistical analyses (<i>α</i> = 0.05).</p> Results <p>L showed the highest 4PBFS and BFS, irrespective of aging. Consistent correlations between the 4PBFS and BFS were found in all groups. L showed the highest Weibull characteristic strength under all conditions. T showed the highest nanoindentation hardness and Young’s modulus, and the Vickers hardness of L and P were lower than other groups. Aging led to surface uplifts and microcracks caused by phase transformation, particularly in L and P.</p> Conclusions <p>The flexural strength of 3Y/5Y-TZP and 4Y/5Y-TZP was comparable to that of 3Y-TZP and 4Y, 5Y-TZP respectively, regardless of aging. Surface roughness showed a marked increase after aging in 3Y-TZP and 3Y/5Y-TZP. Furthermore, the interaction between yttria content and aging was evident across all mechanical and surface characteristics, except for flexural strength.</p> Graphical Abstract <p></p>