The school said it would have no further comment on the firing.
Weiss, 39, joined Jim Harbaugh's offensive staff in 2021 as a quarterbacks coach. He was promoted to co-offensive coordinator in 2022.
Before landing at Michigan, Weiss worked under Harbaugh's brother, John, with the Baltimore Ravens from 2009 to 2020.
"I am proud of the success we achieved over the last two seasons and grateful to all of the Michigan players, coaches and staff. The potential of Team 144 knows no bounds," Weiss said in a statement.
"I have nothing but respect for the University of Michigan and the people who make it such a great place. I look forward to putting this matter behind me and returning my focus to the game I love."
ESPN's Pete Thamel reported Michigan is expected to fire Weiss for cause, meaning they would not have to pay out the remainder of his contract.
The university placed him on leave Tuesday after officials were alerted to allegations of "fraudulent activity involving someone accessing university email accounts without authorization." The incident allegedly took place in late December, and Weiss was officially placed into the police log Jan. 5.
"The University of Michigan Police Department is investigating a report of computer access crimes that occurred at Schembechler Hall during December 21-23, 2022," University of Michigan Deputy Chief of Police Crystal James said in a statement. "Since this is an ongoing investigation there is no additional information to share."
Weiss has not been arrested and said he is "fully cooperating" with the investigation. No further details on what transpired have been made available.