Barozh 12 is a Middle Paleolithic (MP) open-air site located near the Mt Arteni volcanic complex at the margins of the Ararat Depression, an intermontane basin that contains the Araxes River. Sedimentology, micromorphology, geochronology, biomarker evidence, together with an assessment of artifact taphonomy permits the modelling of site formation processes and paleoenvironment at a level of detail not previously achieved in this area. Obsidian MP artifacts were recovered in high densities at Barozh 12 from four stratigraphic units deposited during marine oxygen isotope stage 3 (MIS 3) (60.2 ± 5.7–31.3 ± 3 ka). The MIS 3 sequence commences with low energy alluvial deposits that have been altered by incipient soil formation, while artifact assemblages in these strata were only minimally reworked. After a depositional hiatus, further low energy alluvial sedimentation and weak soil formation occurred, followed by higher energy colluvial (re)deposition and then deflation. Artifacts in these last stratigraphic units were more significantly reworked than those below. Analysis of plant leaf wax (n-alkane) biomarkers shows fluctuating humidity throughout the sequence. Collectively the evidence suggests that hunter-gatherers equipped with MP lithic technology repeatedly occupied this site during variable aridity regimes, demonstrating their successful adaptation to the changing environments of MIS 3.