Multifunctional capability, flexible design, and low-cost manufacturing are desired attributes for wearable and bio-integrated electronics. Piezoelectric materials, in forms that offer the ability to bend and stretch, are attractive for pressure/force sensors and energy harvesters. This chapter discusses how to fabricate flexible/stretchable piezoelectric devices by use of electrohydrodynamical direct-writing technique. The electrohydrodynamical direct-writing utilizes the stable high electrostatic field and tunable mechanical drawing force to produce piezoelectric PVDF nanofibres with the -phase formation through in situ electrical poling and mechanical stretching. Bendable piezoelectric devices can be directly fabricated by depositing the poled nanofiber onto thin polymeric substrate, and generate electricity under bending and lateral pressure. Further, highly stretchable piezoelectric devices are electrohydrodynamically printed by consideration of self-organized in-surface buckling of fiber-on-substrate system. The electrical output of the stretchable energy harvester is characterized that the generated current is linearly ratio to the stretching frequency and strain, as well as the number of nanofibers. Additionally, the stretchable devices generate electrical energy stably by the lateral pressure even in different stretching status. Experimental and theoretical studies provide detailed insights into the energy conversion mechanisms. This chapter provides detailed engineering design rules and paves a cost-effective and high-efficiency manufacturing pathway for applications in wearable and bio-integrated electronics.