Harris and his group will pay more than $320 million to purchase the cash-strapped franchise, The Record of New Jersey reported Wednesday night.
Attorneys for both sides were putting the final touches on the deal Wednesday that would allow Jeff Vanderbeek to sell his majority ownership to Harris, according to The Associated Press.
The Devils announced early Wednesday evening that they planned to hold a major news conference at 11 a.m. Thursday.
The financially strapped Vanderbeek has been looking for a buyer for some time. Harris emerged as the front-runner in the past week after a deal with a group led by Philadelphia attorney Andrew Barroway fell through.
Harris is the co-founder of Apollo Global Management, one of the world's largest private equity firms. He heads a group that includes another equity investor, David Blitzer.
While he owns the 76ers, Harris leases space at the Wells Fargo Center from Comcast Spectacor, which also owns the Philadelphia Flyers.
Having the lease at the Prudential Center, Harris has a chance to earn money from concerts and other events, and he might leverage "The Rock'' as a way to get a better deal in Philadelphia.
A former Devils season-ticket holder since the 1980s, Vanderbeek became a minority owner of the Devils in 2000. He purchased the team and became its majority owner in 2004.
Vanderbeek was one of the leading proponents behind the building of the Prudential Center, which opened as the Devils' home in 2007. The New Jersey Nets also played at the arena before moving into a new home in Brooklyn this past season.
Forbes reported the Devils have $230 million of debt and that Vanderbeek missed the first payment on a recently restructured bank loan.
The Devils won the Stanley Cup in 1995, 2000 and '03, and won additional Eastern Conference championships in 2001 and '12. They missed the playoffs in the recent lockout-shortened season and were then stunned when 30-year-old superstar forward Ilya Kovalchuk decided to play in his native Russia.
The Devils moved to New Jersey in 1982, playing at the Meadowlands after relocating from Colorado.
ESPN.com's Scott Burnside and The Associated Press contributed to this report.