Jonathan Todd Schwartz, 48, of Los Angeles, was charged with wire fraud and filing a false tax return for failing to report the embezzled funds, prosecutors said.
Schwartz admitted stealing nearly $5 million from Morissette between May 2010 and January 2014. He used the money personally and falsely listed the cash withdrawals as “sundry/personal expenses” to cover up the crime.
When confronted about the theft, Schwartz lied and said he invested the money in an illegal marijuana growing business, prosecutors said.
Schwartz also admitted to stealing $2.3 million from five other clients who were not named in court documents or disclosed by attorneys in the case.
Defence lawyer Nathan Hochman said Schwartz had fully co-operated with investigators and accepted responsibility.
He faces up to 23 years in federal prison if convicted, though his plea deal calls for a sentence between four and six years.
Schwartz had worked for GSO Business Management, a company whose website touts the financial guidance it provides to several high-profile celebrities. A company representative said Schwartz no longer worked there.
Morissette sued Schwartz last year in Los Angeles Superior Court, but the lawsuit was dismissed after GSO and Morissette announced a settlement. Morissette’s publicist had no comment.
Schwartz is scheduled to appear Feb. 1 in U.S. District Court.