Martinez was appointed as head coach in August 2016, since which 12 victories and four draws have been recorded from 17 matches.
Belgium and Martinez are currently preparing for the World Cup, but the nation's governing body has moved to announce that Martinez now has a deal until 2020.
An RBFA statement read: "Thanks to his Premier League past, Martinez is close to the world of the current generation of Red Devils, with whom he maintains close ties.
"The contract between the two parties was extended according to the same conditions as in 2016. Within this context, the RBFA appreciates Roberto Martinez' passionate motivation to continue to reinforce the Red Devils in the future.
"The fact that, from his appointment in 2016, he visited different football clubs and academies and observed numerous players during official matches, contributes to his drive to continuously strengthen the Belgian team."
Belgium face fixtures with Panama, Tunisia and England in the group stages of next month's tournament in Russia.