WASP-4b is an exoplanet, specifically a hot Jupiter, approximately 891 light-years away[5] in the constellation of Phoenix.

[6] The planet was the discovered by the Wide Angle Search for Planets team using images taken with the SuperWASP-South project's eight wide-angle cameras located at the South African Astronomical Observatory.

[7][8][1] Analysis of over 4000 images taken between May and November 2006 resulted in the detection of a transit occurring every 1.3 days.

Follow-up radial velocity observations using the Swiss 1.2-metre Leonhard Euler Telescope confirmed that the transiting object was a planet.

The anomalously high rate of orbital decay of WASP-4b is poorly understood as of 2021.