"Bottom line is, after all of your looking and all the time you had and all the money you spent, did Trump collude with the Russians? No - Do you stand by your report? - Yes," Graham said, envisioning questions the special counsel likely will be asked.
"It is 'case-closed' for me. They can do anything they want to in the House, and I think it will blow up in their face.
"It will blow up in their face. This will blow up in their face. The conclusions can't change, there is no collusion, that's what the whole thing was about to begin with."
The Senate Judiciary Committee chairman added that the facts of the case will show President Trump did not restrict Mueller's investigation.
"The president gave 1.4 million documents to Mueller. [Don] McGahn, his lawyer, testified for 30 hours," he said.
"He made everybody available to Mueller that Mueller wanted to talk to, and he... answered questions in writing, so this president did nothing to stop Mueller from finding the truth."
Graham said regardless of Mueller's testimony, it would be hard to prosecute Trump for obstruction of justice.
"There's nobody on Earth who could bring an obstruction case based on these facts," he said.
Mueller has agreed to testify before the House Judiciary and Intelligence Committees on July 17, according to the panels' chairmen, Jerry Nadler, D-N.Y., and Adam Schiff, D-Calif.
Congressional Democrats have fought to get access to Mueller and his unredacted report on Russian interference in the 2016 presidential election and whether President Trump obstructed justice.
“Americans have demanded to hear directly from the Special Counsel so they can understand what he and his team examined, uncovered, and determined about Russia’s attack on our democracy, the Trump campaign’s acceptance and use of that help, and President Trump and his associates' obstruction of the investigation into that attack," Nadler and Schiff said in a joint statement.
Mueller did not immediately comment. In a news conference last month in which he delivered his first public remarks in more than two years, the special counsel said he did not wish to appear before lawmakers.
Fox News' Louis Casiano contributed to this report.