According to a list of new hires by the administration, the daughter of Gray campaign chair Maureen Green and the son of Gray's Chief of Staff Gerri Mason Hall were hired last month.
Green's daughter, Leslie, works in the city's Office of Motion Picture and Television Development.
Hall's son, Nicholas, has been hired as a writer/editor in the Department of Parks and Recreation.
The list was obtained through a Freedom of Information Act request.
D.C. is governed by federal nepotism rules, and there is no evidence any laws were broken.
The mayor's office says while Gray was not personally responsible for the hirings, he stands by them.
The statement adds these young people "were interviewed and selected because of what they can offer" and calls them "the next generation of leaders."
This story was updated at 2:50 p.m. The original post stated that Leslie Green works for the mayor's office as a senior communications manager. A Gray spokeswoman says Green now works in the Office of Motion Picture and Television Development.New Hires In D.C. Government
Virginia's attorney general Ken Cuccinelli will face former Democratic National Committee chairman Terry McAuliffe in November to become Virginia's 72nd governor.