Hughes fought off competition from first division rivals to land his man, a long-term target, and said that the new stadium helped swing Duffy his way.
Hughes said: "I've been after him for ages. He's at an age where he has to prove himself but he scored goals for Rangers under-21s and I'm hoping he can bring that here.
''I know a number of other first division clubs were after him but we had him down at the stadium and he was impressed by what he saw. I have high hopes for him and I'm sure he'll become a firm favourite with the fans."
Duffy made first team debut for Rangers in a 6-0 CIS Cup thrashing of Forfar at Ibrox in October. He came on as a substitute in the Gers Champions League match with Panathinaikos last December after making his league debut as a substitute in a league match against Dundee United three days earlier.
He slipped through Falkirk's fingers when he went on loan to Brechin City in January. There he hit three goals in eight games before being injured.