The jet, which was Nairobi-bound, crashed six minutes after take off.
The Ethiopian Airlines Corporate Communications Director Asrat Begashaw said there were 33 nationalities on board, and the airline is due to hold a press conference shortly.
The Boeing 737 passenger jet, which was new, is said to have had 149 passengers with eight crew on board.
The airline, in a statement, said the plane left Addis Ababa before the accident at Bishoftu.
"The aircraft B-737-800MAX with registration number ET-AVJ, took off at 8.38am local time from Addis Ababa, Bole International Airport, and lost contact at 8.44am," the airline said in a statement.
“At this time, search and rescue operations are in progress and we have no confirmed information about survivors or any possible casualties.”
President Uhuru Kenyatta took to Twitter to offer his condolence message, saying, "We are saddened by the news of an Ethiopian Airlines passenger aircraft that is reported to have crashed 6 minutes after takeoff en route to Kenya. My prayers go to all the families and associates of those on board."
Ethiopian Prime Minister Abiy Ahmed also sent condolences to the affected families.
Deputy President William Ruto said, "Saddened by news of an incident involving an Ethiopian Airlines scheduled flight to Nairobi this morning with 149 passengers and 8 crew. Our thoughts and prayers are with the families whose loved ones were on board."
AU Envoy Raila Odinga said, "My deeply felt condolences to the people of Ethiopia following the crash of the Ethiopian Airlines plane. My prayers are with the families and relatives of victims."
On his Twitter page, he said, “The Office of the PM, on behalf of the Government and people of Ethiopia, would like to express it’s deepest condolences to the families of those that have lost their loved ones on Ethiopian Airlines Boeing 737 on regularly scheduled flight to Nairobi, Kenya this morning”.