The House of Representatives committee demanded the pro-Trump lawyers hand over documents and sit for depositions on February 8.
Representative Bennie Thompson, the committee's chairman, says the panel expects the lawyers to join the nearly 400 witnesses who have spoken with the select committee as part of its investigation into the causes of the deadly attack by Trump supporters.
The committee also subpoenaed Boris Epshteyn, a Trump political adviser.
Robert Costello, a lawyer for Giuliani, said in an interview the subpoena was "political theatre" and his client was constrained by the legal doctrines of lawyer-client privilege and executive privilege.
"I don't think there's anything here he can testify about," Costello said.
Powell, Epshteyn, and Ellis did not immediately respond to requests for comment.
"The four individuals we've subpoenaed today advanced unsupported theories about election fraud, pushed efforts to overturn the election results, or were in direct contact with the former president about attempts to stop the counting of electoral votes," Thompson said in a statement on Tuesday.
Powell, Giuliani, and Ellis jointly spoke at a Trump campaign news conference on November 19, 2020, where they vowed to overturn President Joe Biden's election victory. Powell promised to "release the Kraken," likening their effort to a mythological sea monster.
The Trump campaign distanced itself from Powell after she claimed without evidence at the news conference that electronic voting systems had switched millions of ballots from Trump to Biden.
Giuliani's New York law licence was suspended in June after a state appeals court found he made "demonstrably false and misleading" statements that widespread voter fraud undermined the election, won by Democrat Joe Biden.
The committee aims to release an interim report in the summer and a final report in autumn, a source familiar with the investigation said last month.
CNN reported on Tuesday that the committee has subpoenaed and obtained records of phone numbers associated with one of Trump's children, Eric Trump, as well as Kimberly Guilfoyle, who is engaged to Donald Trump Jr.
