Devices based on transition metal dichalcogenide nanotubes hold great potential for electronic and optoelectronic applications. Herein, the electrical transport and photoresponse characteristics of a back-gate device with a channel made of a single tungsten disulfide (WS2) nanotube are investigated as functions of electric stress, ambient pressure, and illumination. As a transistor, the device exhibits p-type conduction, which can be transformed into ambipolar conduction at a high drain-source voltage. Increasing ambient pressure enhances the p-type behaviour, while exposure to light has the opposite effect, enhancing n-type conduction. The ability to operate the device as either a p-type or n-type transistor makes it promising for complementary metal-oxide-semiconductor (CMOS) circuit applications. Light enhances the conductivity, allowing for further control and enabling the device to function as a photodetector with a photoresponsivity of about 50 mA W-1 and a broadband response in the visible range. The combination of voltage, pressure and light control paves the way for using the WS2 nanotube transistor as a multifunctional device.