Baerbock said Ukraine, facing its third winter of war, needs support to ensure its very survival.
Her visit comes on the eve of the US presidential election, in which a win for Republican candidate Donald Trump could cast doubt on future support from Ukraine's top military backer.
"We are countering this brutality with our humanity and support so that Ukrainians can not only survive the winter but so that their country can survive. Because they are also defending the freedom of all of us in Europe," said Baerbock, embarking on her eighth visit to Ukraine.
Germany has emerged as Ukraine's top donor of military aid in Europe and has closely coordinated its support with Washington.
However, if Trump beats Democrat Kamala Harris in Tuesday's election, this close coordination could falter. Trump has criticized the level of US support for Kyiv and declined to say he wants Ukraine to win the war, which he says he would end quickly by pushing for a negotiated settlement.
The German foreign minister, who was last in Ukraine in May, is due to meet Ukrainian President Volodymyr Zelenskiy and Foreign Minister Andrii Sybiha while in the capital.
Baerbock said Germany had recently extended its emergency energy aid to Ukraine by an extra 170 million euros ($185 million) in response to bombed-out heating plants and power lines.
Since August, Russia has intensified its attacks on Ukraine, in what Kyiv officials say is Moscow's attempt to destroy critical infrastructure needed for heating during winter.
Russia will have to pay for the billions of euros in damage it has caused, said Baerbock, but until that happens, the Group of Seven (G7) will support Kyiv with some $50 billion in loans.
Under incumbent President Joe Biden, the US finalized its $20-billion portion of that amount with a pledge to pay it out in December, timing meant to shield the loan funds from a potential claw-back from Trump.
SD/