The precise decoration of bimetallic nanocrystals (NCs) with uniform size and homogeneous composition on metal oxide (MOX) surfaces is crucial for developing highly sensitive and selective MOX-based gas sensors. In this study, MOX-based gas sensors are present decorated with homogeneous Au-Pd bimetallic (Au@Pd) NCs synthesized via seed-mediated sequential reduction of Au and Pd on an array of TiO₂ nanohelices (NHs) matrix. Due to the uniform composition, size, and dispersion of the bimetallic NCs, the sensor exhibits outstanding toluene (C₇H₈) sensing performance. The optimized Au@Pd NC composition (Au:Pd = 55:45) facilitates chemisorbed oxygen spillover and electronic sensitization, achieving an exceptionally high response (R_a/R_g) of ≈130 000 and rapid response/recovery (69 s/4 s) toward 100 ppm of C₇H₈ at 200 ^°C. Furthermore, the homogeneity of Au@Pd NCs enhances selectivity by providing controlled active sites, yielding a 1008-fold higher response to toluene compared to acetone. Density functional theory calculations and mechanistic experiments reveal that Au@Pd NCs generate toluene-selective catalytic sites that enable complete oxidation. The findings demonstrate that homogeneous core-shell bimetallic NCs can be uniformly integrated on a highly porous MOXs-based gas sensing matrix, enabling exceptional selectivity and sensitivity for advanced gas sensor applications.