The former Republican presidential nominee, who once considered Christie as a vice presidential running mate, has remained a loyal ally of the embattled governor during a bridge scandal that threatens to derail his 2016 ambitions.
Romney will speak during dinner at the fundraiser, before holding a special meeting with Christie and donors, The Washington Post reported Saturday.
Christie is the chairman of the Republican Governors Association, a position that Romney used to hold during his time as Massachusetts governor.
Christie was in Washington Saturday for the National Governors Association annual meeting at the JW Marriott hotel, where his aides told The Post that Romney would join him at next week's RGA fundraiser.
He plans to skip a governors' meeting at the White House on Sunday morning, as he returns home to New Jersey.