"I made a mistake with this guy [Milanic]. He is negative, he has a losing mentality," Cellino told the Yorkshire Evening Post this evening.
"He has three points from six games, that is relegation [form]. Neil Redfearn will take training on Monday. He is the new head coach, 100%."
Redfearn took temporary charge of the club earlier in the season after the departure of Dave Hockaday and had a record of three wins and one draw as caretaker.
Since then, Leeds have lost three and drawn three under former Sturm Graz boss Milanic to drop to 18th in the Championship.
His sacking comes after the Whites threw away a 1-0 half-time lead to lose 2-1 to Wolverhampton Wanderers at home this afternoon.