Nicole Kidman has publicly acknowledged ex-husband Keith Urban for the first time since their divorce, sharing a touching Father's Day tribute.

The Oscar-winning actress, 59, posted on Instagram Stories on Monday honouring the important fathers in her life, posting a pair of black-and-white family photographs.

The first image showed a young Nicole smiling as she cuddled up to her late father, clinical psychologist Antony Kidman, alongside the message: 'Happy Father's Day to all the fathers.'

In the second photo, Keith was pictured carrying daughters Sunday Rose, now 17, and Faith Margaret, now 15, on his back in a sweet throwback moment.

The post marks her first public gesture to her former partner after Keith, 58, wished Nicole a happy birthday over the weekend.

On Saturday, the country music superstar shared a simple but meaningful tribute to his former wife on Instagram as she celebrated her 59th birthday.

Posting a blue and purple graphic, Keith wrote: 'Happy birthday Nicole Mary!'

By including her middle name, Mary, the singer added a personal touch to the brief message.

Nicole's Father's Day tribute appears to signal a united front despite the breakdown of their nearly two-decade marriage.

The former couple announced their separation in last September after almost 20 years together, with their divorce officially finalised by a judge in Nashville, Tennessee, on January 6 this year.

The message also comes amid reports Nicole has quietly moved on romantically.

According to celebrity gossip site Deuxmoi, the Others actress has been enjoying a low-key romance with a 'high-profile businessman' for several months.

'We're told the relationship has been quietly developing for the past few months and the pair have been keeping things extremely low-key and largely out of the public eye,' a source claimed.

Earlier this year, TMZ also reported that MGM Resorts International chairman Paul Salem, 62, had expressed interest in the Australian actress.

The publication noted the pair share mutual friends and had met socially on two occasions, but stressed they were not dating at the time.

Meanwhile, Keith appeared to make another subtle nod to his former wife when he attended the ACM Awards in Las Vegas in May.

As he posed on the red carpet, fans noticed he was still wearing tattoos dedicated to Nicole, including the word 'Mary' inked across his fingers in tribute to her middle name, along with symbolic wrist designs linked to their relationship.