Roman Calderon claims the Portuguese coach will sign a three-and-a-half year deal at the Bernabeu to take over from Santiago Solari .
And Calderon revealed the deal could be completed in the coming days.
Calderon said: “I understand Mourinho will sign a deal for the remainder of this season and for another three years, with a net salary of £17m per year, possibly as early as Monday.
“He will return because something needs to be done and president Florentino Perez believes Mourinho is the best man he can get at this time — one of the worst periods in the club’s history.”
Current boss Solari is under increased pressure after Madrid were eliminated from two cup competitions in the space of a week.
The Los Blancos were knocked out of the Champions League by Ajax, which was followed by two defeats to rivals Barcelona – the second of which saw them lose ground in the title race.
Madrid are now set to turn to Mourinho, who would return to the club where he spent three years in charge from 2010-2013.
Mourinho has been out of a job since being sacked by Manchester United in December.
Calderon said of the 52-year-old: “Mourinho will be the perfect shield against the unhappiness in the media, the fans and the players.
“But it will not be easy and I predict it will be very difficult over the next three months.”