EU leaders have accepted Ukraine and Moldova as candidates to join the bloc, opening a path to membership that's likely to take a number of years.
President of the European Commission Ursula von der Leyen tweeted that it was a historic moment and a "good day for Europe".
"Your countries are part of our European family," she added.
Ukraine's President Zelenskyy said: "Sincerely commend EU leaders decision", and added "Ukraine's future is within the EU".
The move is likely to anger Russia which has long opposed the prospect of Ukraine joining the EU.