The 28-year-old will make the move to the Spanish capital after Atletico reportedly met his 25m pounds (35m euros) release clause.
Atletico’s sporting director Jose Luis Perez Caminero expressed his satisfaction with the deal,telling the club’s official website: "We are very pleased with the agreement, because Jackson Martinez is an extraordinary striker, able to rapidly solve any attacking play inside the box. Thanks to his size, he heads very well and interchangeably uses either foot to shoot. I am sure that he will greatly increase the potential of our team and will bring plenty to the group. We are delighted with his signing because he is a football player used to competing at a top level in Porto and has shone brightly in important competitions such as the Champions League."
Martinez, capped 38 times by his country, spent three seasons at the Estadio do Dragao scoring 92 goals in 133 games, as well as 13 in 24 Champions League games. He helped the Portuguese club to the league title in 2013 as well as two Super Cup wins in 2012 and 2013.