The Shutter Island star says she already thinks about the significance watching her late father Heath Ledger onscreen will have for her daughter.
'It was the place where I met Matilda’s father, and that is a lot,' Williams said when asked by US magazine Angeleno what the 2005 movie means to her.
She added: 'It was a lot. And it will be a lot for Matilda too, when she gets around to watching it.
'I will watch it with her, when she’s ready. It is hard to imagine what that would feel like, but one day, yes, we will watch it together.'
The Blue Valentine star also admits that she feels as though she has been through a lot, given that she is still only 30.
She said: 'I have taken on a lot of things earlier than would be the standard in terms of working, of being in a serious relationship and having a child.
'I was 25 when I had Matilda, and so I feel like I have caught up to myself, and 30 feels like a number that maybe matches all those things a little bit better.'