She did not answer questions from reporters as she entered the building.
Officials said that within hours of the 9 a.m. conversation, a rough transcript compiled by aides had been moved from a widely shared White House computer network to one normally reserved for highly classified intelligence operations.
President Donald Trump and Ukrainian President Volodymyr Zelenskiy looks on during a meeting in NY on September 25, 2019, on the sidelines of the United Nations General Assembly. The two are accused of funnelling foreign money into the campaigns of rightwing politicians-including lawmakers who specifically wanted to get Yovanovitch (who did not love corruption as much as they seem to) out of the way.
At the time, the officials were unnerved by the removal in May of the USA ambassador to Ukraine, by subsequent efforts by Trump's lawyer Rudolph W. Giuliani to promote Ukraine-related conspiracies, as well as by signals in meetings at the White House that Trump wanted the new government in Kiev to deliver material that might be politically damaging to Democratic presidential candidate Joe Biden. Biden is a leading Democratic contender seeking his party's nomination to face Trump in the 2020 presidential election.
There has been no evidence either Biden was engaged in illegal activities. Trump has denied that charge, but acknowledged he blocked the funds, later released.
Zelensky agreed with Trump that she was a "bad ambassador". According to Yovanovitch, Sullivan said the president no longer wished for her to be his ambassador because he had lost confidence in her.
Yovanovitch, a respected 30-year career diplomat, was attacked by Giuliani and others who embraced an unproven, right wing conspiracy theory that the ambassador was part of a liberal scheme to bring down former Trump campaign chairman Paul Manafort, who pleaded guilty to fraud and lying to federal officials.
California Democrat Adam Schiff arrives on Capitol Hill on Friday.
Eric Rubin, president of the American Foreign Service Association that represents US diplomats, said Yovanovitch's testimony was in "the proud tradition of our nation's Foreign Service, emphasizing non-partisan commitment to our country's interests and loyalty to our country's elected leaders".
She was born in Montreal to Russian parents, her family moving to the USA a few years later.
Zelenskiy invited US and Ukrainian prosecutors to cooperate on an eventual investigation into the Bidens, but insisted he would not interfere. The committees are intelligence, foreign and oversight. They said their subpoena was in response to learning that the State Department had directed Yovanovitch to not appear before Congress on Friday, a direction that she defied.
Sondland, a Trump political donor who contributed $1 million USA to the Republican president's inauguration committee, exchanged text messages about Washington's relationship with Ukraine with other top diplomats. On Thursday, Trump renewed his attacks on Twitter, describing the impeachment inquiry as a "Democrat Scam". He was confirmed by the U.S. Senate in June and presented his credentials at the European Commission in July.
In a text with another USA official, Bill Taylor, Sondland denied there was a quid pro quo in the White House's dealings with Ukraine.
A day earlier, U.S. prosecutors arrested two Florida businessmen tied to Giuliani, charging them with campaign finance violations.
The pair, Ukraine-born Lev Parnas and Belarus-born Igor Fruman, were arrested at an airport outside Washington carrying one-way tickets to Vienna. Not only did she appear for her scheduled deposition, but boy did she have a lot to say.
An anonymous intelligence community whistleblower filed a complaint about the call, accusing Trump of leveraging his office and withholding USA aid to Ukraine to obtain "dirt" on a political opponent-2020 Democratic candidate Joe Biden.
Yovanovitch is a career diplomat who previously served as a United States ambassador to Kyrgyzstan and Armenia.
Mr Parnas sought the help of a United States congressman to get Mr Trump to remove Ms Yovanovitch, according to the indictment.