Sources at Stamford Bridge say they expect the deal to go through, while those close to the 24-year-old say a full agreement has already been reached on a contract to run until 2032, with an option for the club to extend it by a further two years.
Internally, the Brazil international is regarded as a major success after joining from Brighton in a deal worth an initial £55m, plus £5m in add-ons, last summer.
Last season, Joao Pedro became the first Chelsea striker since Diego Costa to score 20 goals in a campaign without taking a penalty. He also scored three times during Chelsea's Club World Cup-winning campaign last summer and has netted eight goals in seven pre-season matches this time around.
Joao Pedro is likely to start Chelsea's Premier League opener at Fulham, with new signings Danny Welbeck and Emmanuel Emegha expected to provide cover this season.
His success has led Chelsea to hand him the number nine shirt, with Liam Delap relinquishing it. Delap is available for transfer for around £50m and is attracting interest from Nottingham Forest and Leeds United.
Chelsea intend to hand out a number of new contracts to key players once the transfer window closes, with Levi Colwill and Estevao Willian among those likely to be considered.
The forward's rise since arriving in west London has been swift. He finished last season as Chelsea's Player of the Season after scoring 23 goals in all competitions, and manager Xabi Alonso has made clear he expects even more from the Brazilian this time around.
Barcelona were among the clubs to express interest in Joao Pedro earlier in the summer, reportedly ready to test Chelsea's resolve with an offer worth in excess of £100m, but the club have consistently made clear that he is not for sale, regardless of the fee on the table.