A Bola reports that Martinez will announce a new long-term deal with the Portuguese giants in the coming days.
His agent, Luis Manuel Manso, told the Renaissance: "It's okay, I will travel in a week to Porto to discuss the renewal."
And when pressed as to whether the framework to the new deal had already been agreed, he continued: "Yes, there is already an agreement to renew."
The news will come as a blow to Chelsea and Arsenal, who had been linked heavily with the Colombian international this month.
He signed for Porto in 2012 for €9m, chiefly to replace Radamel Falcao, and has since bagged 38 goals in 44 league appearances for the club. His contract is believed to include a €40m release clause.
His impressive strike rate saw him linked with Chelsea and Arsenal, both of whom were believed to be looking for another striker heading into the January transfer window.
He alerted both Chelsea and Arsenal to his potential availability late last year when he said he followed both Premier League clubs as a boy growing up in Colombia.
But, the latest report all but ends the Gunners hopes of landing the forward.
It's particularly relevant for Arsenal as they are still believed to be scouring the market to add competition for Olivier Giroud.
Chelsea meanwhile, have ruled out adding another forward to their ranks - although that may change following the knee ligament injury suffered by Fernando Torres.