The 44-year-old got 167 votes, almost double the 88 votes needed to win, while high-ranking German diplomat Helga Schmid received seven votes as a write-in and 14 countries abstained.
Germany had nominated Schmid for the assembly presidency but replaced her with Baerbock after she lost her job as the country's foreign affairs chief in the recent election. The decision drew some criticism in Germany.
When Baerbock appeared before the assembly to discuss her candidacy on May 15, Russia's deputy UN ambassador Dmitry Polyansky lashed into her, saying: "Ms Baerbock has repeatedly proved her incompetence, extreme bias and lack of understanding of the basic principles of diplomacy."
Polyansky accused her of having pursued an "anti-Russia policy", which he said gave Russia reason to doubt that as General Assembly president she would be "able to act in the interests of peace and dialogue".
Baerbock will replace current assembly president Philemon Yang, a former prime minister of Cameroon, at the start of the 80th session in September. She will preside over the annual gathering of world leaders in late September and anniversary events marking the founding of the United Nations in 1945.
The one-year presidency of the General Assembly rotates by region.
"I am grateful … the overwhelming majority of member states have voted in favour of my candidacy and I'm looking forward to work with all member states together in these challenging times," Baerbock said on Monday.
The assembly, which is the UN 's most representative body, has taken the spotlight in reacting to the wars in Ukraine and Gaza. That's because any action by the UN Security Council has been blocked by the veto power of Russia on Ukraine and the United States on Gaza.
