Part of the Semien Mi'irabawi Zone, Tahtay Adiyabo is bordered on the south by the Asigede Tsimbela, on the southwest by the Tekezé River which separates Tahtay Adiyabo from the Mi'irabawi Zone, on the north by Eritrea, and on the east by La'ilay Adiyabo ; part of the northern border with Eritrea is delineated by the Mareb River.