  We use photometry from the recent AllWISE Data Release of the Wide-field
In-frared Survey Explorer (WISE) of 129 calibration stars, combined with prior
distances obtained from the established $M_V-$[Fe/H] relation and Hubble Space
Telescope trigonometric parallax, to derive mid-infrared period--luminosity
relations for RR Lyrae pulsating variable stars. We derive relations in the W1,
W2, and W3 wavebands (3.4, 4.6, and 12 {\mu}m, respectively), and for each of
the two main RR Lyrae sub-types (RRab and RRc). We report an error on the
period--luminosity relation slope for RRab stars of 0.2. We also fit posterior
distances for the calibration catalog and find a median fractional distance
error of 0.8 per cent.
