The Rev. Corey Brooks said he wired Kilpatrick the money during the holiday season after he received a pleading letter from the ex-mayor, the Detroit Free Press reported.
Kilpatrick was forced to resign as mayor in 2008 and then served 14 months in prison.
WJBK-TV, Detroit, said a security video shows Kilpatrick collected the wired money at a Michigan Walmart, pocketing $800 of it and then wiring the rest to his family, now living in Texas.
Michigan authorities are now investigating whether Kilpatrick deceived them by not including the money in his required report of income and gifts.
Kilpatrick, his father and a friend are on trial in federal court, accused of rigging contracts.
The Chicago Tribune said Brooks is called the "rooftop pastor," as he's best known for camping out on the roof of a Chicago motel for three months last winter to raise funds to demolish the haven for drugs and prostitution and build a new community center.