89 Aquarii (abbreviated 89 Aqr) is a binary star system in the equatorial constellation of Aquarius. 89 Aquarii is the Flamsteed designation, though it also bears the Bayer designation c<sup>3</sup> Aquarii. The apparent visual magnitude of +4.69 is bright enough to be seen with the naked eye. Its distance from Earth is roughly , based upon parallax measurements with an 11% margin of error.
The primary component of this system has a magnitude of 5.27 and a stellar classification of G3 II, which suggests this is an evolved star in the bright giant stage. The companion is an A-type main sequence star with a stellar classification of A2 V. As of 2010, it is located at an angular separation of 0.1843 arcseconds along a position angle of 135.1ð. They orbit each other with an estimated period of 201 years and a semimajor axis of 0.45 arcseconds.