Loftus-Cheek has just two years left on his existing deal and a long-term extension will come as a big boost for Chelsea at a time when the club is hamstrung by a transfer ban.
According to the Daily Telegraph, an official announcement on Loftus-Cheek's new deal is expected to 'roughly coincide' with the appointment of manager Frank Lampard on Wednesday.
The newspaper explains the fresh contract will run for 'at least' the next five years and will see Loftus-Cheek's weekly wages almost trebled from £60,000 to £150,000.
That means over a five-year period the contract could be worth as much as £39m.
Loftus-Cheek, who played 40 games for Chelsea in all competitions last season - the most of his professional career to date, is currently nursing a ruptured Achilles suffered during a post-season friendly against New England Revolution at the end of May.
With a six-month layoff expected, the 23-year-old is tipped to return to action around November time. Assuming there are no setbacks, he could then prove to be an important player in Lampard's debut season in the Stamford Bridge hot seat.
The pair were never first team colleagues, with Lampard leaving in 2014 shortly before Loftus-Cheek graduated to the senior squad. But the latter had been part of the youth academy for 10 years prior to that and so Lampard will have been aware of his talent from an early age.
As well as Loftus-Cheek, teenage winger Callum Hudson-Odoi is also expected to soon commit his long-term future to Chelsea, having flirted with a transfer to Bayern Munich in January. He is another nursing an Achilles injury and won't feature in the first months of the Lampard regime.
Source : 90min