Ratcliffe's INEOS Group is taking a 25% interest in the company at $33 per share, valuing the 20-time English champions at $6.3billion including debt, a source familiar with the matter said.
Under the deal, INEOS will also manage Manchester United's soccer operations after the Glazer family's long-time ownership came under fire for the club's poor performance over the past decade.
Manchester United's stock has surged about 52% after the Glazers announced in November last year that they were exploring strategic options, including a sale, for the club.
Since former manager Alex Ferguson stepped down in 2013, the club has seen five permanent managers and three caretakers but has failed to recapture its glory days, winning just four trophies in 11 years.
Ratcliffe's INEOS Sport owns France's OGC Nice, which stands second in Ligue 1 only behind Paris Saint-Germain, majority-owned by investment fund Qatar Sports Investments.
The Gulf country's Sheikh Jassim bin Hamad Al Thani had also considered buying the club, but dropped out of the process saying he would not raise his $6billion offer.
INEOS also owns FC Lausanne-Sport, which is in the relegation-threatened tenth position in the Swiss Super League.
Manchester United has been knocked out of European competitions and are eighth in the Premier League table despite heavy investments over the past several years to bring in popular players.
