By Agence France-Presse
Abiy had just ended his speech in the heart of the capital Addis Ababa when the explosion went off, sending the crowds towards the stage as the prime minister left hurriedly, apparently safe and sound.
The cause of the blast was unknown and it was not immediately clear if there were any casualties.
Since taking office in April, Abiy has made major changes in Ethiopia including releasing jailed dissidents and moving to liberalise the economy.
He succeeded Hailemariam Desalegn, who resigned in February amid a wave of anti-government protests led by the country's two largest ethnicities, that started in late 2015 and left hundreds of people dead.