Flexible thermoelectrics provide a different solution for developing portable and sustainable flexiblepower supplies. The discovery of silver sulfide–based ductile semiconductors has driven a shift in thepotential for flexible thermoelectrics, but the lack of good p-type ductile thermoelectric materials hasrestricted the reality of fabricating conventional cross-plane p-shaped flexible devices. We report aseries of high-performance p-type ductile thermoelectric materials based on the composition-performance phase diagram in AgCu(Se,S,Te) pseudoternary solid solutions, with high figure-of-meritvalues (0.45 at 300 kelvin and 0.68 at 340 kelvin) compared with other flexible thermoelectricmaterials. We further demonstrate thin and flexible p-shaped devices with a maximum normalizedpower density that reaches 30 mW cm−2 K−2. This output is promising for the use of flexiblethermoelectrics in wearable electronics.