Nicole Kidman shares a gushing tribute to her husband Keith Urban as she celebrates his birthday

They are the A-list couple who have never been afraid to show their affection for each other.

And on Thursday, Nicole Kidman shared a sweet tribute to her husband Keith Urban as she celebrated his 55th birthday.

The actress, 55, shared a photo on Instagram of herself and her husband hugging and sharing a kiss at an event.

“Happy Birthday my love…4ever,” she captioned the image, adding love heart emojis.

Nicole and Keith married on June 25, 2006, after meeting at an event last year.

The couple tied the knot at Cardinal Cerretti Chapel on the grounds of St Patrick’s College in Manly, Sydney.

A-list guests including Hugh Jackman and wife Deborra-Lee Furness, along with Naomi Watts and director Baz Luhrmann were in attendance.

Nicole’s two adopted children, Isabella, 29, and Connor, 27, who she shares with ex-husband Tom Cruise, acted as bridesmaids and ushers.

The couple later welcomed daughters Sunday Rose, 14, and Faith Margaret, 12, in 2008 and 2010.

Keith recently admitted to turning his back on partying to focus on his family with his wife Nicole.

The country singer publicly battled drug and alcohol addiction and went to rehab several times. The last time he attended the Betty Ford Center was in October 2006, just months after marrying Nicole.

Now Keith has admitted that his marriage is an important factor in staying sober and out of trouble.

“I’d like to stay married!” Keith told The Sun. ‘Nightly I hate myself during the day, it’s so true. But the next morning at night I am nowhere to be found – he is totally inexplicable.’

Keith added: “Life is very different these days. I try to be a good example for the kids, but I still don’t know if I’m doing it right.

“I’ve made so many mistakes, but you have to find what works for you. My message to them is always to do what they are passionate about, I don’t care as long as they work hard to achieve it.’

Keith said it helps him stay sober by staying on top of his successful career which includes touring, releasing music and working as a mentor for The Voice Australia.