CD&R has acquired a “significant stake” in B&M in a deal that values the retailer at around £965m.
The sale establishes the Arora family as one of the wealthiest in the UK.
Simon, Bobby and Robin Arora bought B&M in 2005 when it was loss-making and had fewer than 20 stores.
However, the retailer has been transformed since then. It now has more than 300 stores, 100 employees, and annual sales of £1bn,
The Arora brothers will retain a stake in B&M and stay involved with the business, which is based in Liverpool.
Sir Terry is an adviser to CD&R and his role as chairman is his first significant management position since stepping down as chief executive of Tesco in 2011.
In a statement, the Arora brothers said: “We are delighted to have the opportunity to partner with CD&R.
“We are proud of the success we have had with B&M since acquiring it in 2005, but recognise that we need a partner to bring the expertise to ensure the business fulfils its overseas potential.”