Commission President Ursula von der Leyen thanked him for his "tireless" work.
The government here said Phil Hogan had chosen "the correct course of action" after the GolfGate scandal -- and will name his successor "in due course".
The Trade Commission he has given up is one of the most powerful jobs in Brussels.
Labour leader Alan Kelly says if Ireland has any hope of keeping it, the government needs to put a new name on the President's desk by the weekend.