Osmia maxillaris are black bees with blue-green metallic luster. O. maxillaris have golden brown hair that covers the vertex and thorax, and the remaining hair on the legs and face is whitish. T1–T5 have whitish to yellow apical hair bands (Müller 2012). Hair can bleach out with time, and older bees can have gray hair (Peters 1978). Female body length is 11–13 mm, and male body length is 12–14 mm (Morawitz 1876).
Osmia maxillaris looks similar enough to O. scheherazade that O. scheherazade was considered a subspecies of O. maxillaris until it was raised to species status by Müller (2012). The easiest way to distinguish these species is by the shape of T7, which is more angulate and medially emarginate in O. scheherazade and entire and evenly convex in O. maxillaris.
Osmia maxillaris adults have been recorded in flight from the middle of May to the middle of June (Peters 1978).
Osmia maxillaris are oligolectic on Fabaceae and have preference for flowers with deep corolla tubes such as Astragalus (Müller 2012).
Osmia maxillaris specimens have been recorded in Central Asia. O. maxillaris are distributed in Kyrgyzstan, Tajikistan, and Uzbekistan (Müller 2012).