Some Democrats quickly mocked the Trump announcement.
"I am assuming this investigation will look into Russian interference with our elections," said Rep. Ruben Gallego (D-AZ).
"The great political crisis we face is not voter fraud, which barely exists," said Sen. Bernie Sanders (I-VT). "It's voter suppression and the denial of voting rights."
While Mr. Trump has long argued that there was widespread fraud in 2016, he has never offered any evidence to back up that claim.
In Congress, there has been no appetite for such an investigation, as many Republican lawmakers say they have no evidence of widespread fraud, either.
It was not immediately clear what agency would lead the review, how broad an investigation would take place, or what type of report might be produced.
"I’ve seen no evidence of that, I’ve made that very, very clear," said House Speaker Paul Ryan.
Elections officials in a variety of states have echoed that assessment as well.
"To claim, without a shred of evidence, that millions of ‘illegal votes’ were cast does nothing but undermine people’s confidence in democracy," said Connecticut Secretary of State Denise Merrill, a Democrat.
Natalie Tennant, a former West Virginia Secretary of State, labeled Trump's voter fraud charge, the "Lie that won't die."
"Saying it over and over doesn't make it true," said Kentucky Secretary of State Alison Grimes, who is also a Democrat.