Barker, 22, has signed a three-year deal with the Scottish Premiership club, having been at Preston last term.
"Last year I didn't feel we had enough in the final third," Gerrard said.
"The idea this year was to build a squad with exciting players who can open the door in different ways."
Barker himself said there was "no better place" for him to develop himself than Rangers.
"It's a massive club and the name speaks for itself," Barker told Rangers TV. "The people working here had a massive influence, too."