Wales captain Ramsey has been tasked with leading the Bluebirds to safety, with the club second from bottom and one point off the safety zone.
The 34-year-old Ramsey, who has no managerial experience but long-held aspirations of moving into coaching, will lead the side in Monday's home game against Oxford United.
Supporting Ramsey will be his ex-international teammate, Wales Under-19s manager Chris Gunter, plus midfielder Joe Ralls.
"We’d like to thank Omer for his passion and effort during his time as Cardiff City manager and wish him the very best for his next steps in the game," Cardiff said in a statement.