New Deputy Chairman Announced
Bates named McGuinness as his personal assistant at Stamford Bridge in 1995, and she remained with the 73-year-old until Roman Abramovich took control of the London club last year.
McGuinness, a former architect who worked with Chelsea during the vast reconstruction of the club's stadium and village complex, becomes the fifth member of United's board alongside Bates, finance director Yvonne Todd, who held the same position at Chelsea, and directors Mark Taylor and Peter Lorimer.
McGuinness, who will hold responsibility for day-to-day decisions at boardroom level, said: "This is a very big challenge. Leeds have had a couple of very difficult years."