Ukraine is "one of us and we want them in the European Union", Ursula von der Leyen has told Euronews.
The interview came after Brussels announced it was sending weapons to Ukraine, banning Russian-backed media in the EU and prohibiting Russian aircraft from the bloc.
But despite backing Ukraine for EU membership, she gave no indication it would be the rapid accession demanded by President Volodymyr Zelenskyy on Saturday.
Von der Leyen told Euronews: "We have a process with Ukraine that is, for example, integrating the Ukrainian market into the single market.
"We have very close cooperation on the energy grid, for example.
"So many topics where we work very closely together and indeed over time, they belong to us. They are one of us and we want them in."
Von der Leyen also said trust in Vladimir Putin is "completely broken and eroded".
Discussing the possibility of peace talks between Ukraine and Russia, she said: "Of course, it is important that the Ukrainian side agrees to the peace talks and that conditions are fine for the Ukrainian side. In general, it is always better to have peace talks than to have a fight. But the trust in President Putin is completely broken and eroded."
Watch the entire interview with European Commission President Ursula von der Leyen in the player at the top of the page.