Zn₃As₂ is an important p-type semiconductor with the merit of high effective mobility. The synthesis of single-crystalline Zn₃As₂ nanowires (NWs) via a simple chemical vapor deposition method is reported. High-performance single Zn₃As₂ NW field-effect transistors (FETs) on rigid SiO₂/Si substrates and visible-light photodetectors on rigid and flexible substrates are fabricated and studied. As-fabricated single-NW FETs exhibit typical p-type transistor characteristics with the features of high mobility (305.5 cm² V⁻¹ s⁻¹) and a high I_on/I_off ratio (10⁵). Single-NW photodetectors on SiO₂/Si substrate show good sensitivity to visible light. Using the contact printing process, large-scale ordered Zn₃As₂ NW arrays are successfully assembled on SiO₂/Si substrate to prepare NW thin-film transistors and photodetectors. The NW-array photodetectors on rigid SiO₂/Si substrate and flexible PET substrate exhibit enhanced optoelectronic performance compared with the single-NW devices. The results reveal that the p-type Zn₃As₂ NWs have important applications in future electronic and optoelectronic devices.