The 43-year-old actress said her directorial debut was never planned, and she had initially envisaged producing and starring in the script by writer Anthony Tambakis, The Hollywood Reporter said.
But after the project failed to draw investors and directors to the movie, Zellweger decided to step up to the role, and she is delighted with the project's progress.
"Anthony sent the script to me last year, asking thoughts and whether I'd partner with him to produce it. I'm such a fan of his writing. He has an ability to capture worlds with remarkable compassion, humour and intimacy and the truth of his characters' humanity is felt in every line.
"I couldn't get the script out of my head, but we didn't have a director and weren't making any headway. During a work session for (new TV drama) 'Cinnamon Girl' in early 2012, I brought up '4 1/2 Minutes again', Anthony suggested I direct, and it all started rolling from there."
