The swearing-in ceremony was held as part of the first day of the Ethiopian House of Peoples' Representatives (HoPR)'s new five-year term.
Abiy's ruling party Prosperity Party's won a landslide victory in national elections held in June.
He then was appointed by the HoPR and the lower house of the Ethiopian Parliament as Prime Minister
Following his appointment, Ahmed is expected to form a new cabinet, which will form the new federal government structure.
He was first appointed as the country's Prime Minister in April 2018.
He had served the East African country at different high-level positions, including as Minister of Science and Tchnology.
Ahmed's Prosperity Party secured more than 400 out of 436 parliamentary electoral constituencies, according to the National Electoral Board of Ethiopia.
Visit news.dtnext.in to explore our interactive epaper!
Download the DT Next app for more exciting features!
Click here for iOS
Click here for Android