The series, which starred Welling as Clark Kent, began in 2001 and concluded after a ten-year run last month.
Welling told OnTheRedCarpet: "It would've been fun to do a... movie for those characters. But who knows in the future. I don't see why [we couldn't]."
The actor also revealed that the producers of Smallville had considered releasing a film based on the series back in 2004.
"We talked about [doing] that between... season three and four, when the characters were moving from high school to... college," he explained. "We played with the idea [but] there wasn't time."
Welling added that he is looking forward to watching Zack Snyder's new Superman film, which will star Henry Cavill as the Man of Steel.
"They have other plans for Superman, which I'm a big fan of and I can't wait to see what they do," he said.
Welling's former co-star Erica Durance (Lois Lane) previously revealed that she was open to a new Smallville project featuring the show's original cast.
"Get everybody in the same place and then we'll see," she said. "It's one of those things where you get [attached]. You kind of have a thing for your own Superman. You don't want to trade him in!"
> Smallville execs 'thrilled by finale controversy'