Ford, 73, reprises his role as the debonair Han Solo in the seventh Star Wars instalment, The Force Awakens, set thirty years after the events of Return of the Jedi.
"In the passage of 30 years Han Solo has come to understand more about the nature of the force than he did in the first film," Ford told a packed forecourt, adding that the film franchise transcended culture and countries.
"For that I'm grateful."
Asked about the new Star Wars Ford said, "its a real ride" adding that there was "substantial emotional exercise involved".
"I think basically it's stories about growing up, independence, responsibility, loyalty, doing the right thing. It's a hero's journey."
After heckling from the crowd, Ford said his next project would be the next instalment of Blade Runner.
The Opera House played host to a fan event ahead of the premier of Star Wars: The Force Awakens next week.
Jay Laga'aia, who plays Captain Gregar Typho in the prequel films and appears in the latest film, said he had been a fan of the films all of his life.
"When I got the call, I called my cousins and that just to brag to them and they couldn't believe it either," he told ABC News on the red carpet, adding that his character survives the film.
"We're all guessing what it was all about but at the end of the day, as a true fan you go, 'listen I'm not going to think about this'."
The hotly anticipated film has been shrouded in secrecy, its two leads Daisy Ridley and John Boyega, relative unknowns.
Ridley plays a scavenger called Rey and Boyega a redeemed First Order storm trooper called Finn.
Fans of all ages packed into the Opera House forecourt, some waiting since the morning.
"We were driving all night because we came from Melbourne," said Sarah Cooper who was dressed as Han Solo.
"It's just an amazing opportunity for Star Wars fans to come together.
"We grew up with Harrison Ford's stories, we grew up with Han Solo, we grew up with Indiana Jones, it's such a staple of the better years of our lives," said Rod Fletcher, who was dressed as Indiana Jones and drove up with Sarah and two other friends from Melbourne.