The Middle–Upper Eocene Rashrashiyah Formation of the Sirhan–Turayf Basin, northwestern Saudi Arabia, yields a diverse assemblage of deep-marine agglutinated benthic foraminifera representing the first well-documented assemblage from the Arabian Plate. Twenty-three species assigned to ten genera were identified from an ~11 m interval and correlated with planktonic foraminiferal Zone E14 (Priabonian). The fauna is dominated by Haplophragmoides, Spiroplectammina, Plectina, Pavonitina, Karreriella, and Flabellogaudryina, with Pavonitina styriaca, Pavopsammia flabellum, Plectina spp., Karreriella arenasensis, and Clavulinoides alpina reported for the first time from Saudi Arabia. Morphogroup and diversity trends reveal an upward transition within the upper Slope Marl Assemblage (SMA). The lower part of the studied succession corresponds to the lower subdivision of the upper SMA and is characterized by oxygen-stressed assemblages dominated by Haplophragmoides with Psammosphaera and Saccammina, whereas the upper part of the succession represents the upper subdivision of the upper SMA and is marked by communities dominated by Karreriella, Plectina, and pavonitinids (Pavonitina, Pavopsammia) associated with the Oxygen Minimum Zone (OMZ). The assemblage shows strong paleoecological and taxonomic affinity with OMZ-related Priabonian slope faunas from Hungary, Italy, and southern Bulgaria. These findings significantly extend the known southern Tethyan distribution of several agglutinated taxa and establish the Sirhan–Turayf Basin as a key reference locality for reconstructing Late Eocene benthic foraminiferal paleoecology and upper-slope environmental conditions along the southern margin of the Tethys.