Together with two other planets[a] in the Proxima Centauri system, it is the closest known exoplanet to the Solar System, located approximately 4.2 light-years (1.3 parsecs; 40 trillion kilometres; 25 trillion miles) away in the constellation of Centaurus.

The first signs of the exoplanet emerged as a weak 5.15-day signal in radial velocity data taken from the Very Large Telescope during a 2020 study on Proxima b's mass.

This signal was formally proposed to be a candidate exoplanet by Faria et al. in a follow-up paper published in February 2022.

It is the least massive exoplanet detected with the radial velocity method as of 2022[update].

Although Proxima d orbits too close to its star to have a habitable equilibrium temperature (which likely reaches 360 K (87 °C; 188 °F)[1] from about 190% of Earth's irradiation—assuming an Earth-like reflectivity, it is theoretically possible that Proxima d possesses polar regions with habitable temperatures.