Archaeobotanical investigations at the site of Ona Adi in Tigrai were conducted during the 2013–2015 field seasons within the framework of the Eastern Tigrai Archaeological Project (ETAP). The site occupation spanned the Middle/Late Pre-Aksumite period (ca. 750/600 BCE) to the fall of the Aksumite Kingdom (ca. 700 CE), including the Pre-Aksumite to Aksumite transition (ca. 400 BCE–CE 1). The main objective of the study was to examine the agricultural economy in Eastern Tigrai during these periods and to evaluate the impact of social and cultural developments on the agricultural practices at Ona Adi. Recovered macrobotanical remains included wheat, barley, linseed, noog, lentil, and wild/weedy plants. In addition, evidence of finger millet was recovered along with tentative identifications of t’ef. The phytolith record shows evidence of grass processing, including morphotypes associated with Chloridoideae, Panicoideae, and Pooideae grasses. Results indicate that plants of both African and Southwest Asian origins were present in the region from the mid-eighth century BCE to the eighth century CE, but their relative importance varied throughout time in relation to socio-political changes at the regional level. Our data demonstrate a significant degree of continuity in the local agricultural economy, which remained largely unchanged even after the decline of Aksumite state.