The Australian actress, 52, made a brief appearance at a pre-Golden Globes event in Los Angeles on Saturday (US time), looking visibly upset.
Kidman's representative told Us Magazine that the couple are "keeping a close eye" on their rural property, which is "under threat" from the NSW wildfires.
The Oscar winner refused red carpet interviews, saying she was "so distracted".
"I'm so sorry. I'm so distracted right now with everything that's happening in Australia," she apologised, according to attendees.
Eyewitnesses at the Gold Meets Golden event said Kidman maintained her composure and left the red carpet after 15 minutes.
Both Kidman and Whangarei-born Urban, who identifies as New Zealand-Australian, announced they were donating $500,000 to the Rural Fire Services on Saturday afternoon (US time).
"Our family's support, thoughts and prayers are with everyone affected by the fires all over Australia. We are donating $500,000 to the Rural Fire Services who are all doing and giving so much right now," Kidman wrote to her six million Instagram followers, alongside a list of links to donate to local state fire services.
The couple, who have been married since 2006, are believed to own two homes in Australia including a vast Sutton Forest farm and Sydney penthouse in New South Wales.
The bushfires have burned more than 12 million acres of land nationwide. Dozens of people remain unaccounted for and an estimated half a billion animals are believed to have perished in the fires.