This study presents a novel approach to achieve high strength and ductility in multi-principal element alloys (MPEAs) by harnessing premature necking during Lüders banding. In conventional metallic materials, the strength-ductility trade-off is a major challenge, especially at ultrahigh yield strengths, where ductility is significantly reduced due to the difficulty in producing and accumulating dislocations. The research focuses on a VCoNi MPEA, which contains local-chemical-order (LCO) regions as built-in heterogeneities. These LCO regions, along with the microstructure, enable the rapid multiplication of dislocations during Lüders banding, leading to enhanced work hardening through both forest dislocation hardening and interactions with LCO regions. This dual hardening mechanism helps to stabilize premature necking and promote uniform deformation, resulting in a significant improvement in both strength and ductility. The VCoNi MPEA achieves a yield strength of 2 GPa and a ductility of ~20% at room temperature and cryogenic conditions. The study demonstrates that by utilizing the instability of premature necking, it is possible to achieve a synergistic balance between strength and ductility in high-strength materials. The findings provide a new paradigm for controlling instability to enhance work hardening and overcome the strength-ductility paradox in ultrahigh yield strength materials.This study presents a novel approach to achieve high strength and ductility in multi-principal element alloys (MPEAs) by harnessing premature necking during Lüders banding. In conventional metallic materials, the strength-ductility trade-off is a major challenge, especially at ultrahigh yield strengths, where ductility is significantly reduced due to the difficulty in producing and accumulating dislocations. The research focuses on a VCoNi MPEA, which contains local-chemical-order (LCO) regions as built-in heterogeneities. These LCO regions, along with the microstructure, enable the rapid multiplication of dislocations during Lüders banding, leading to enhanced work hardening through both forest dislocation hardening and interactions with LCO regions. This dual hardening mechanism helps to stabilize premature necking and promote uniform deformation, resulting in a significant improvement in both strength and ductility. The VCoNi MPEA achieves a yield strength of 2 GPa and a ductility of ~20% at room temperature and cryogenic conditions. The study demonstrates that by utilizing the instability of premature necking, it is possible to achieve a synergistic balance between strength and ductility in high-strength materials. The findings provide a new paradigm for controlling instability to enhance work hardening and overcome the strength-ductility paradox in ultrahigh yield strength materials.