The club made the announcement late tonight with just hours of the transfer deadline day left.
McKinnon had taken training at Morton this morning before news of his impending move broke this afternoon. The Greenock side were preparing for tomorrow’s match with Partick Thistle. John Sutton will now take the Championship’s joint leaders at Firhill.
The announcement ends four days of uncertainty for Bairns fans since Paul Hartley and the club parted ways on Monday following the 3-0 defeat by QOS.
McKinnon has previously managed Brechin City, Raith Rovers, Dundee United and Morton who he joined in May. He leaves the Greenock side joint top, second on goal difference, in the Ladbrokes SPFL Championship.