Justin Bieber surprises Ellen DeGeneres

Justin Bieber made a surprise appearance during Ellen DeGeneres's monologue on today's episode of her show.

The comedienne had been encouraging the audience to buy her wife Portia De Rossi's book Unbearable Lightness when Bieber crept out from backstage holding a copy of his own book.

"I heard you were talking about books and stuff and I'm coming out with a book called First Step 2 Forever and I wanted to give it to you," he said.

DeGeneres then asked if Bieber would sign the book he was holding as she dictated the message she wanted him to write. "To Ellen," she said. "I love you - not heart, I love you. You are my best friend in the whole wide world. I can't imagine life without you. I remember when we first met..."

The 'Baby star' then interrupted to say he had run out of room to which DeGeneres replied: "You can add more later!"

Bieber then led DeGeneres in a dance routine to Usher's 'Yeah' before mingling with the audience and hugging some of his female fans.

The full interview airs today.