<p>A gradient architecture, consisting of an α_p/β_T component with a gradient in density and various microstructural features, was developed along the longitudinal (Y) direction using an appropriate temperature gradient, based on the phase transformation characteristics of the α + β dual-phase Ti6242 alloy. In this architecture, a larger strain ε_yy occurs in the soft domain without any constraint in the Y direction, causing more contraction than in the hard domain along the other (X/Z) directions. This incompatible contraction between adjacent domains in the X/Z directions efficiently activates a multiaxial stress state throughout the gauge volume. The contraction deformation is accommodated by a sudden multiplication of geometrically necessary dislocations near the domain boundary. Consequently, this leads to increased activation of the pyramidal &lt; c + a &gt; and &lt; a &gt; slip systems, which require higher critical resolved shear stress. Furthermore, additional strain hardening occurs, explaining the enhanced ductility, particularly the reduction in area, without strength loss at lower volume fractions (<i>V</i>_<i>f</i>) of the gradient layer, and a continuous increase in strength accompanied by slight ductility loss at <i>V</i>_<i>f</i> ≥ 50%. These findings provide new insights into designing large-scale gradient materials with a favorable strength-ductility synergy using this longitudinal architecture.</p>