The 50-year-old, who signs a deal until the end of the 2017/18 campaign, beat off competition from over 50 candidates to land the role and become Steve Evans' successor at the AESSEAL New York Stadium.
Redfearn made it through a vigorous selection process, including two interviews, with Hibs manager Alan Stubbs believed to have been pipped to the post.
A club statement read: "Rotherham United are delighted to announce the appointment of Neil Redfearn as the club’s first team manager.
"The former Leeds United boss has penned an agreement until the end of the 2017/2018 season to join the Millers, and he will be officially unveiled at a press conference at AESSEAL New York Stadium on Monday afternoon.
"Redfearn came out on top after a meticulous selection process where he impressed Chairman Tony Stewart and the Board of Directors with his vision for the future of the club.
"The 50-year-old, who has vast experience of coaching at all levels, plus experience of managing at Championship level, will speak about his new appointment for the first time on Monday.
"Redfearn also enjoyed a long and illustrious playing career which included spells in the Premier League with Barnsley, Charlton Athletic and Bradford City, whilst he also enjoyed time with the likes of Crystal Palace, Oldham Athletic and Doncaster Rovers."
Redfearn has been out of work since leaving Leeds in the summer after a tumultuous spell.
The Yorkshireman had three spells in caretaker charge of the Elland Road club while academy manager before eventually getting the job on a permanent basis last October.
Despite chaos off the field under the stewardship of Italian Massimo Cellino, he led Leeds away from relegation in the Championship and to mid-table safety.
However, that was not enough for him to keep his job and, despite being allowed to return to his previous role with the academy when Uwe Rosler was appointed, he found the position untenable and left in July.
Redfearn is credited with developing young talent while at Leeds, with Alex Mowatt, Lewis Cook and Sam Byram all coming through the ranks, and that is a skill that impressed Millers chairman Tony Stewart.
