It puts an end to the 13 years in power of her left-wing Workers' Party. Ms Rousseff had denied the charges.
Sixty-one senators voted in favour of her dismissal and 20 against, meeting the two-thirds majority
needed to remove her from the presidency.
Michel Temer has been sworn in as president and will serve out Ms Rousseff's term until 1 January 2019.
The centre-right PMDB party politician had been serving as acting president during the impeachment proceedings.
During his first cabinet meeting since the vote, Mr Temer said his inauguration marked a "new era".
He asked his ministers to "vigorously defend" the government from accusations that Ms Rousseff's dismissal amounted to a coup d'etat.
"We can't leave one accusation unanswered," he said during the meeting, which was broadcast live on television.
He also told ministers to work closely with the Congress to revive the Brazilian economy. Mr Temer is travelling to China to take part in a summit of the G-20 group of major economies.
The dismissal of Ms Rousseff has caused a rift between Brazil and three left-wing South American governments that criticised the move later on Wednesday.
Brazil and Venezuela recalled each other's ambassadors. Brazilian envoys to Bolivia and Ecuador have also been ordered home.