Tahtay Adiyabo (Tigrinya: ታሕታይ ኣድያቦ, lit. 'Lower Adiyabo') is a woreda in the Tigray Region of Ethiopia. Part of the North Western Zone, Tahtay Adiyabo is bordered on the south by Asigede Tsimbela, on the southwest by the Tekezé River 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. The northernmost point of this woreda is the northernmost point of Ethiopia. Towns in this woreda include Addi Awuala and Addi Hageray. The town of Sheraro is surrounded by Tahtay Adiyabo.