Brand said he could not resist the 29-year-old beauty, reported Daily Mirror.
"She's so gorgeous, just so gorgeous and I was chatting her up and got the conversation around to have you got a boyfriend. And then you know that feeling of how long do I have to entertain a conversation?" Brand said.
Kunis was already in a long-term relationship with child star Macaulay Culkin and had ignored Brand's attempts to woo her.
"Then I go away and she keeps talking about her boyfriend Mac, this is when I was on 'Forgetting Sarah Marshall'. Then when he came it wasn't Mac - it was Macaulay Culkin. He'd got longer and looked pale and scared of himself, like a shaved horse. There was a horror about him and I thought, 'That's the lad from Home Alone'," Brand said.