There had been speculation that Trump would use his executive privilege to block Comey's testimony, but the White House issued a statement on Monday saying this would not be the case.
A special counsel is looking into links between Trump's presidential campaign a year ago and Russians who sought to influence the election by hacking Democrats.
Comey is scheduled to testify for the first time since his firing before the Senate Intelligence Committee as part of the committee's Russia-related investigation.
Comey's associates have indicated that he felt uncomfortable as USA president had sought to "compromise" FBI's independence. "Hoping on Thursday we actually get some good answers with Comey".
Last week, White House Press Secretary Sean Spicer fielded reporter questions on the matter but didn't rule out the executive privilege option.
Comey is scheduled to speak publicly for the first time since he was sacked and since several news outlets reported that his memos showed that Trump sought to persuade him to drop his probe into former National Security Adviser Michael Flynn.
Comey, ousted last month amid a federal investigation into connections between Russian Federation and the Trump campaign, is set to testify before Congress next week in a highly anticipated hearing that could shed new light on his private conversations with the president in the weeks before the firing.More news: PAL flights to Qatar unaffected by diplomatic row
Trump told NBC News he believed Comey to be a "showboat" and "grandstander".
"In the context of a criminal investigation, executive privilege has to give way", said Saikrishna Prakash, who lectures on constitutional law and the separation of powers at the University of Virginia in Charlottesville.
Anticipation over Comey's appearance will return the administration to a state of siege, which has been partially lifted in recent weeks during Trump's foreign trip and the build up to his decision to quit the Paris climate pact.
"I think that the president is often very effective in driving our message in Congress", said Short, who argued that the president won the election because he was "not a conformist candidate" and voters were anxious for change in Washington.
The White House will also be pushing legislation to combat human trafficking, spearheaded by the president's daughter and adviser, Ivanka Trump.
Protesters assembled in Washington and other US cities on Saturday in a "March for Truth" to demand an independent investigation into alleged connections between Trump's campaign and Russian Federation.