PERHAPS they saved the fireworks for their bedroom, but Nicole Kidman managed to keep a super secret birthday party for husband Keith Urban on Saturday night under the radar.

Until now, that is.

While Urban celebrated his wife's 40th with a pyrotechnics display in June this year, Kidman arranged a more intimate affair for his milestone.

The dinner, at the couple's favourite Bondi restaurant, Icebergs, was kept to just 45 family and friends, including Urban's parents and Kidman's family.

A source told Confidential a "beautiful'' home movie, created by Kidman, was "a loving tribute from everybody'' to the country boy made good.

"It wasn't an overly lavish affair, just a really nice dinner for just close family and friends. They had a great time,'' the insider said.

Hugh Jackman and wife Deborra-Lee Furness arrived at the party late, joining his Australia director Baz Luhrmann, Catherine Martin, Jack Thompson and Ben Mendohlson for the festivities.

A live band entertained guests, while Urban spent time catching up with several of his old muso mates, also on the guest list.

The party continued for the happy couple on Sunday, when Kidman walked the red carpet with her husband at the ARIAs for the first time.

Keen to keep out of Urban's spotlight, the actress appeared coy on camera, after he paid tribute to her ``inspiration'' when picking up the best country album award.