There's something about Renee.
The Brigid Jones Diary star stunned onlookers at Elle's 21st Annual Women in Hollywood event at in Los Angeles.
But it wasn't her simple lace black shift dress or Louboutin heels that drew attention - Renee's face was almost unrecognisable.
The petite actress's features looked remarkably different, prompting speculation that she had some cosmetic surgery.
Zellweger (45) debuted a wrinkle-free forehead and it her eyes appeared wider and brighter.
Some experts however suggested that the biggest transformation was in her eyebrows, which were unkempt and less defined.
But the Chicago actress today dismissed suggestions that she had opted for surgery and said her new look was simply down to being happy.
"It seems the folks who come digging around for some nefarious truth, which doesn't exist won't get off my porch until I answer the door," the 45-year-old Oscar winner told People magazine after the event.
"I'm glad folks think I look different! I'm living a different, happy, more fulfilling life and I'm thrilled that perhaps it shows.
"My friends say that I look peaceful. I am healthy," she added.
"For a long time I wasn't doing such a good job with that. I took on a schedule that is not realistically sustainable and didn't allow for taking care of myself."
"Rather than stopping to recalibrate, I kept running until I was depleted and made bad choices about how to conceal the exhaustion. I was aware of the chaos and finally chose different things," she added.
Zellweger stars in upcoming movie The Whole Truth with Keanu Reeves.