Senators voted to suspend her by 55 votes to 22 after an all-night session that lasted more than 20 hours.
Vice-President Michel Temer will now assume the presidency while Ms Rousseff`s trial takes place.
The trial may last up to 180 days, which would mean Ms Rousseff would be suspended during the Olympic Games in Rio de Janeiro, which start on 5 August.
Ms Rousseff made a last-ditch appeal to the Supreme Court to stop proceedings, but the move was rejected.
Ms Rousseff, who was first sworn into office in January 2011 and started a second term in 2015, has called the steps to remove her a "coup".
In a speech at the end of the all-night Senate session, attorney general Jose Eduardo Cardozo said that the impeachment request did not have legal basis and that the opposition wanted to remove a democratically-elected president.
He said senators were condemning an "innocent woman" and that impeachment was a "historic injustice".
Who is stand-in President Michel Temer?
The 75-year-old law professor of Lebanese origin was Ms Rousseff`s vice-president and was a key figure in the recent upheaval
Up until now, he`s been the kingmaker, but never the king, having helped form coalitions with every president in the past two decades
He is president of Brazil`s largest party, the PMDB, which abandoned the coalition in March
In recent months, his role has become even more influential; in a WhatsApp recording leaked in April, he outlined how Brazil needed a "government to save the country".
-1780923278.jpg&h=190&w=280&zc=1&q=100)
