Herein we describe the use of temperature-responsive poly(ionic liquid) (PIL) smart hydrogels based on tributylhexyl phosphonium sulfopropyl acrylate (SPA) as fully integrated temperature-operated valves in microfluidics. The mechanism behind the temperature response of the PIL is the presence of a lower critical solution temperature (LCST). When the temperature was increased from 20 °C to 50 °C, the SPA hydrogels showed an area contraction by 44.92 ± 1.16 % (n = 3). Following this, the PIL hydrogels were integrated in a microfluidic device as reversible fully operational temperature-controlled valves in a temperature regime from 20 °C to 50 °C.