"We are very happy to be back in Australia," they said in a joint statement carried by Australian Associated Press. "We have come home to celebrate our wedding with our family and friends."
Australian media have widely speculated that Kidman, who will be 39 on Tuesday, and Urban, 38, will wed June 25 at a Catholic church in a northern Sydney suburb close to where Kidman, who was born in Hawaii, attended high school.
The Oscar-winning actress was photographed leaving a private jet as she arrived in Sydney early Monday.
Kidman told People magazine last month that she and Urban were planning to marry. "He's actually my fiance," she told the magazine after hosting a gala event in New York. "I wouldn't be bringing my boyfriend."
Urban's publicist, Paul Freundlich, later confirmed the couple were "happily engaged."
Kidman won an Oscar for 2002's The Hours. Urban won a Grammy in 2006 for best male country vocal performance for "You'll Think of Me."
Urban and Kidman were first seen together last year.
Kidman and Tom Cruise divorced in 2001 after 10 years of marriage. The couple have two children, Isabelle and Connor.
Katie Holmes, who is engaged to Cruise, gave birth to the couple's first child, a daughter, Suri, in April.
Keith Urban, Vince Gill host all-star concert
Oct 13, 2009 2:00 am PDT
Keith Urban and Vince Gill will co-host an all-star concert Tuesday to raise money for the Country Music Hall of Fame and Museum. Others confirmed to perform at Nashville's Sommet Center are Taylor Swift, Brad Paisley, Faith Hill, Jason A...
Keith Urban goes with instinct on digital release
Jul 23, 2009 7:00 pm PDT
Keith Urban's contribution to the iTunes Originals series features interview segments and new, live-in-studio recordings of six songs -- including three from his latest album, the chart-topping "Defying Gravity." On the just-released ...
Urban tries to protect his daughter from cameras
May 7, 2009 11:00 am PDT
Keith Urban understands that paparazzi come along with the fame, but he draws a line when it comes to his infant daughter. "I'm as protective of my family as any father and husband can be. It can be just a bit intrusive, you know," he sai...
Faced with soft economy, artists offer deals
Apr 9, 2009 7:00 am PDT
If you want to sit in the really good seats for a Keith Urban concert this summer, a pair of tickets will put you about back about $170. But in a nod to the tough economic times, the country superstar has also priced some tickets as low as...
Apr 8, 2009 10:00 am PDT
No disrespect to Kelly Preston, but it looks like Nicole Kidman married the real Urban Cowboy. Fresh off last weekend's win at the Academy of Country Music Awards, Keith Urban roped in his first No. 1 album as Defying Gravit...