The surprise hearing will be held on Tuesday. A spokesperson for the House January 6 select committee had no comment on the focus of the hearing or witnesses who would testify.
Congress is in recess until before the July 4 Independence Day holiday, and the panel had not been expected to hold additional hearings until next month.
The committee has held five hearings on last year's deadly insurrection when former president Donald Trump's supporters stormed Congress as it sought to formalise Democrat Joe Biden's victory over the Republican in the 2020 presidential election.
The panel's chairman, Democratic representative Bennie Thompson, said it would hold additional hearings after the first five.
"Those hearings have spurred an influx of new information that the committee and our investigators are working to assess," he said on Thursday.
Many of Trump's fellow Republicans have testified as the committee laid out what it said was Trump's seven-part plan to overturn the election.
Multiple aides or officials close to Trump, however, have refused to co-operate with the investigation.
At the last hearing on Thursday, top US Justice Department officials testified that Trump contacted them daily in his final weeks in office to pressure them to help him illegally hold on to power.
Trump sought to replace acting attorney-general Jeffrey Rosen with Jeffrey Clark, a Justice Department environmental lawyer and staunch supporter of Trump's false claims that his defeat was the result of widespread fraud.
That move was headed off only when most of the rest of Justice Department leadership threatened to resign en masse if Trump carried it out.
The US Justice Department is conducting its own investigation of the January 6 attack, including whether there was a plot to advance alternative slates of fake electors in battleground states with the goal of overturning the election.
