The 'Younger' actress has five-year-old Luca Cruz with her former husband Mike Comrie, and has admitted the tot has "no clue" about her fame as he's still a little too young to understand.
Hilary said: "Luca has seen me on the cover of a magazine before in the grocery store, but I think he thinks that, like, the next day, it's the next mommy's turn to be on it. Like, he has no clue."
But the former 'Lizzie McGuire' actress admits she's "not ready" for her son to know everything about her celebrity status, as he once came home from school claiming he "knows" who she is.
Hilary, 29, told 'Good Morning America': "Luca came home from school - I picked him up from school - and when we got home, he's like: 'I know. I know your name.'
"I was like: 'I know.' And he's like: 'No, no. Your name's Hilary Duff.' And I was like: 'Caught!' Like, I didn't know how to respond. I'm like: 'Yeah, that is my name.'
"But he said it with, like, a little glint in his eye, like somebody told him something that I haven't, and I was like: 'No, I'm not ready for this yet!' You know?"
Meanwhile, young Luca was recently left shocked after his father Mike - who divorced Hilary in 2016 - left him "basically bald" whilst trying to give him a trendy summer chop.
Hilary recalled: "His dad shaved all of his hair off! We discussed it. We're like, 'Let's give him a short summer 'do - like a buzz cut. And then Luca didn't feel like going to get his hair cut, and Mike's like, 'I'm just gonna do it!'
"And then Luca was excited by the thought of his dad cutting his hair. Then he sent me a picture and he was like, 'I might have went a little too short. He's like basically bald.'"
And the mistake hasn't gone unnoticed by Luca, who already misses his blonde tresses.
The 'A Cinderella Story' star added: "He was looking in the mirror, and he told Mike, he's like, 'Dad, I think I miss my golden hair.' And then he felt it and he was like, 'Ooh, but it feels like a peach!'"