The system is located at a distance of several hundred parsecs from the Sun and is one of the three main stars of Orion's Belt along with Alnilam and Mintaka.

[11] Much more recently, in 1998, the bright primary was found by a team from the Lowell Observatory to have a close companion; this had been suspected from observations made with the Narrabri Stellar Intensity Interferometer in the 1970s.

[4] Alnitak is a triple star system at the eastern end of Orion's Belt, the second-magnitude primary having a 4th-magnitude companion nearly 3 arcseconds distant, in an orbit taking over 1,500 years.

In about a million years, it will expand into a red supergiant wider than the orbit of Jupiter before ending its life in a supernova explosion, likely leaving behind a black hole.

[12] A fourth star, 9th-magnitude Alnitak C, has not been confirmed to be part of the Aa–Ab–B group, and may simply lie along the line of sight.

The traditional name Alnitak, alternately spelled Al Nitak or Alnitah, is taken from the Arabic النطاق an-niṭāq, "the girdle".