289 Nenetta is an A-type asteroid with a diameter of 38 km. It was discovered by Auguste Charlois on 10 March 1890 in Nice, France. The asteroid is orbiting the Sun at a distance of 2.87 AU with an eccentricity (ovalness) of 0.204 and an orbital period of 4.87 yr. The orbital plane is inclined at an angle of 6.7° to the plane of the ecliptic.

Photometric observations taken in 2018 provided a light curve showing a synodic rotation period of 6.916±0.001 h for the asteroid with an amplitude of 0.20±0.02 in magnitude. This result is mostly consistent with previous measurements.

The spectrum of 289 Nenetta reveals the strong presence of the mineral olivine, a relative rarity in the asteroid belt.