
Speaking on the blue carpet at the film's London premiere, he says the output from the studio, which owns characters including Batman, Wonder Woman and Shazam, has been "uneven".
While some of its films have been critical and commercial hits, others have flopped or, in the case of Batgirl, been scrapped before they were released.
Fans, too, had complaints about the inconsistent portrayal of characters.
"I want to rebuild the trust of the audience, which I think DC had lost over the years," says Safran.
He and DC co-chief Gunn have been behind the reboot of the DC Universe, which Safran describes as an attempt to bring all of its heroes "under one creative vision".
"We have a big responsibility on our shoulders but we're thrilled with how it's going so far," he says.
As well as Supergirl, the studio also plans to release supervillain horror movie Clayface later this year.
Marvel - long seen as DC's big rival - also has two big releases this year in the form of Spider-Man: Brand New Day and Avengers: Doomsday.
But Safran says competition is healthy.
"That which unites comic book fans is much greater than that which divides us," he says.
"So we want Marvel to do great. And obviously James had his start at Marvel. And so we're keeping our fingers crossed that they have a great winter."
Jesse Figueiras Osorio, 20, and sister Nathalia, 15, turned up at the premiere to catch a glimpse of Supergirl's stars.
The DC fans agree the universe was in need of a restart.
"The characters weren't being portrayed the way that I expected them to," says Jesse.
"James Gunn is doing a really good job of bringing his vision of the characters to life, because he's also just as big as a fan as everyone else is."
Jesse also thinks it's fair to say some fans had lost trust in DC, but she's hopeful the studio can turn things around.
"The trust was definitely lost," she says.
"The Batman vs Superman films were pretty good, but I felt like it wasn't representative of that DC universe.
"This new universe, it's like you're starting to feel the characters warm up.
"And I'm excited."

