The Latics boss is hopeful the 21-year-old will make an instant impact at the DW Stadium.
The Lancashire outfit snapped up Argentina youngster on a three-year deal from Premier League champions Chelsea on transfer deadline day for a fee believed to be in excess of £1million.
The former Blackburn Rovers loanee could make his first start at home to Sunderland on Saturday.
Martinez said: "For us to bring Franco in on an 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."
Meanwhile former midfielder Paul Scharner believes Wigan will be relegated from the top flight this season.
The 30-year-old, who is now with West Brom having been released by the Latics at the end of last season, said: "I fear the squad left does not have enough experience this time."