The poll showed 41 per cent were satisfied, up from 26 per cent when Mr Trump took office.
Among Republicans, 72 per cent were satisfied, a jump of 14 points since December, suggesting impeachment increased his popularity within his own party.
Democrats said the impeachment trial, only the third in US history, was a "sham" because it had no witnesses.
Senior Republicans said it was "time to turn the page" on the saga.
Closing arguments will be made by lawyers for the Democrats and the White House tomorrow before senators make their views known ahead of a vote on Mr Trump's guilt or innocence on Wednesday afternoon.
Mr Trump faces two articles of impeachment - abuse of power and obstruction of Congress - and a two-thirds majority would be needed to convict him.
Republicans hold a 53-47 majority in the Senate and will vote to acquit.
Mr Trump had wanted his acquittal to take place before delivering his State of the Union address on Tuesday and held "fervent" talks with Mitch McConnell, the Senate's Republican leader, in an attempt to achieve that. But moderate Republican senators wanted time next week to explain their decision-making process publicly.
Polls showed a majority of Americans thought witnesses should have been called but Democrats only managed to persuade two Republican senators to vote with them out of the four they needed to carry the motion.
Chuck Schumer, the Democrat leader in the senate, said: "America will remember this day, a day when the United States senate did not live up to its responsibilities, turned away from truth and instead went along with a sham trial."
He said there should be a "permanent asterisk next to the acquittal of President Trump written in permanent ink".
But Lindsey Graham, a senator and friend of the president, said: "The sooner the better for the country, let's turn the page."
Mr McConnell said Democrats had already presented 17 witnesses in the House of Representatives, and there was no need for further ones.
He said: "A majority of the US senate has determined that the numerous witnesses, and 28,000-plus pages of documents, already in evidence are sufficient to judge the accusations."
The impeachment case centred on allegations that Mr Trump tried to pressure Volodymyr Zelenskiy, the president of Ukraine, to open a corruption investigation into Joe Biden, his domestic political rival.
Mr Biden's son Hunter sat on the board of Burisma, a Ukrainian energy company, while Mr Biden was vice president and responsible for US policy on Ukraine.
The Biden family has denied any wrongdoing.
Mr Trump consistently denied doing anything wrong.
