New Castle County police say Justin Mangini had also been wanted for an incident of terroristic threatening.
The robbery occurred last week at the Colonial Village Apartments. Police say Mangini pulled a knife and demanded money from the victim before fleeing the area.
He has been charged with first-degree robbery, possession of a deadly weapon during a felony and conspiracy. He's in custody after failing to post bail and has also been ordered to have no contact with the victim.