Benji Madden has posted a gushing tribute to his wife Cameron Diaz online, saying she is his "best friend".

The newlyweds posed for a cute selfie which Madden posted on his Instagram to mark the actresss's 43rd birthday.

He captioned the photo: "Happy Birthday to my Beautiful Wife.

"My best friend and Everything else- there's so much I could write. I'm the luckiest guy alive - I get to spend the rest of my life right here. I love this Woman!! Many more Baby!!" 

Madden of US pop punk band Good Charlotte and actress Diaz tied the knot in an intimate ceremony at their home in Beverly Hills in January.