Latics pulled off a major coup in snapping up Argentinian starlet Di Santo on a three-year deal from Premier League champions Chelsea on transfer deadline day last week.
Martinez told the Wigan Observer: "For us to bring Franco in on a permanent basis is an important statement.
"He is someone that we want to develop but someone that we need to bring that competition up front and I think he can develop into a top, top striker in the Premier League and in world football.
"I think he can play for Argentina and is someone we have very high hopes for.
"He had to leave Chelsea just to progress his career.
"We're so excited about him as a human being and as a player. Technically he's a player that is probably better than his physique, very powerful in the last third and good movement.
"He's played 4-3-3 with Chelsea and I think he's ready.
"The last year he had at Blackburn was as good a settling period as you're going to get."