Tell Khamîs, an archaeological site of the Syrian region of Upper Jazeera, is 3 km east of the Euphrates and 31 km from Yarâblûs (ancient Karkemiš); archaeological excavations determined seven different levels (Early Bronze, Middle Bronze, Aramaic, Assyrian, Persian, Hellenistic, and Islamic). This study aims to identify plant remains recovered during the excavation of the site and to place them within the chronology of Tell Khamîs and in the context of the archaeobotanical evidence for the Upper Euphrates. A total of 88 sediment samples were collected, and seeds, recovered via flotation, were identified using optical and SEM microscopy. A total of 20,606 whole remains and 37,646 fragments belonging to 92 taxa and 35 plant families were identified. Seed lists were compared with those from other sites, and the results were analyzed using multivariate techniques. Barley is particularly noteworthy for the number of remains; this species was found in 49 different samples, notably, in a silo of about 4 m3 in volume. Middle Bronze Age and Assyrian levels are the richest in remains; the site presents a maximum of documented activity in the Middle Bronze Age period, and the most interesting taxa from a paleoenvironmental and cultural point of view are represented by one or a few seeds.