The drastic temperature rise of multiwall carbon nanotubes (MWCNTs) in response to microwave irradiation was applied to weld a MWCNT paste on a polymer substrate within a few seconds. It provides a strong bonding between the MWCNT and polymer without thermal damage to the substrate. A flexible field emitter was made from MWCNT microwave welded on polycarbonate, showing excellent electrical conduction and field-emission properties even under bending. The field emitter works with a turn-on voltage of 0.8V∕μm due to the direct electron transfer. By this method, printed circuits and field-emission devices can be processed simultaneously within seconds leading to important applications in flexible electronic devices.