In a speech before the documents were sent to the Senate, Pelosi said the House managers would make history by delivering the articles charging Trump with abuse of power and obstruction of the House.
"As we make that history we will be making progress for the American people, progress in support of our Constitution, progress in honor of the sacrifice and the vision of our founders, progress in honor of the sacrifice of our men and women and uniform and progress for the future of our children," she said.
House managers walked the documents to the Senate where they were met by Senate Republican Leader Mitch McConnell, who invited the House managers to present the articles of impeachment on Thursday.
"The Senate is ready to receive the managers of the House with the purpose of exhibiting articles of impeachment against Donald John Trump," McConnell said.
The House voted Wednesday to send the Senate two articles of impeachment against Trump, after Democrats held onto the charging documents for a month hoping to receive some assurances there will be an impartial trial.
The lower chamber voted 228-193 to transmit the articles a short time before the vote, Pelosi assigned seven Democratic lawmakers as case managers for the Senate trial, which is now expected to begin early next week.
The Democratic case managers, who will present the case against Trump at trial, are intelligence committee chairman Rep. Adam Schiff, judiciary committee chairman Rep. Jerry Nadler, and Reps. Hakeem Jeffries of New York, Val Demings of Florida, Zoe Lofgren of California, Jason Crow of Colorado and Sylvia Garcia of Texas.
"Today is an important day," Pelosi said at a press briefing Wednesday morning. "The emphasis is making the strongest possible case to protect and defend our constitution, to seek the truth for the American people.
"The Constitution and our oaths to protect it are at stake. That's what the Senate must consider."
"The managers of the impeachment trial of the president are public servants committed to protecting our Constitution -- and have the litigation and courtroom experience necessary to execute this task," she added in a tweet.
Cipollone and Sekulow will be joined on the team by White House attorneys Patrick Philbin and Michael Purpura, the Washington Examiner reported.
The charges against Trump stem from his dealings with Ukraine last year -- specifically, his efforts pressing Kiev to investigate Democratic presidential candidate Joe Biden and his son, a former board member of a Ukrainian gas company.
In an interview with MSNBC's Rachel Maddow on Wednesday, Lev Parnas, an associate of Trump's attorney Rudy Guiliani, revealed new allegations that Trump had threatened to withhold more than just military aid from Ukraine as was originally claimed unless it investigates the Bidens.
He said he "gave a very harsh message" to a Ukrainian presidential aide on behalf of Trump threatening all U.S. aid would be withheld unless the government announced the investigation.
"It wasn't just military aid, it was all aid," he said.
Parnas also said that Trump "knew exactly what was going on" despite the president's denials of having done anything wrong.
Cipollone, 53, has been a vocal critic of the House's impeachment process and is considered the main force behind White House efforts that blocked most witnesses in the administration from testifying during the lower chamber's inquiry.
An Oct. 8 White House letter called the process "partisan and unconstitutional" and made a case for a broad interpretation of executive privilege covering nearly every aspect of presidential conduct.
Pelosi and Senate Democratic leader Charles Schumer hoped to persuade McConnell to allow certain witnesses and new evidence at trial. The stalemate ended, however, when the Kentucky Republican said this week he's already secured enough support in the chamber to move ahead without Democrats' involvement.
House Democrats released an example of the new evidence on Tuesday -- documents they say show Trump attorney Rudy Giuliani pressed Ukraine to investigate the Bidens. They said the records, provided by an attorney for Giuliani associate Lev Parnas, also indicate U.S. Ambassador to Ukraine Marie Yovanovitch had been placed under surveillance.
Yovanovitch, who was removed from her diplomatic post last May, was among a number of witnesses who testified during the House impeachment hearings. She said Trump mounted a "smear campaign" as retaliation for her opposition to Giuliani's efforts in Ukraine.
In light of the new evidence, Yovanovitch is now calling for an investigation of the surveillance claims, which she called "disturbing."