The 23-year-old has been rubbing shoulders with the likes of Lionel Messi and Sergio Aguero in training and could earn his first cap in Wednesday's friendly with Saudi Arabia.
The call-up is reward and recognition for his form with Wigan since the turn of the year, where he helped the side escape relegation last season before contributing to a solid start this campaign.
Martinez is delighted Di Santo has been called up, especially considering the competition he faces for a striking spot in Argentina's forward line.
"Franco Di Santo is developing into a top footballer," said Martinez. "He's only 23 but he's come on a lot.
"Obviously being called up by Argentina and playing with the likes of Messi and Sergio Aguero is going to do him a lot of good.
"I could see it coming because I work with him every day. You get a bit biased because you know the player.
"We always believed in Franco - we paid big money for our limitations financially. We're just so glad that he's been able to develop into the player that he is today.
"We hope that he can enjoy the experience and come back to help us."
Martinez also feels the call-up reflects well on Wigan and their growing status in English football.
The Latics are enjoying their eighth successive season in the top flight and Martinez thinks they are now getting recognition for the way they play their football.
"I was a little bit surprised with the knowledge the national team coach Alejandro Sabella has shown because, to know a striker at Wigan Athletic, it shows you that they are incredibly professional in the way they follow their players," added the former Swansea chief.
"It's a real compliment to Wigan. The way we play probably attracts the interests of national team managers.
"We didn't do before and that's a real compliment. Franco deserves huge, huge credit for the achievement."