The 36-year-old actress, whose films include Snow White and the Huntsman and Monster, revealed earlier this week that she has adopted a son named Jackson.
Theron told Ryan Seacrest on his radio show: "It's been amazing, the amount of emails and congratulations. Everyone's just been so lovely - it's been really nice."
The star also admitted that her favourite parental pastime is wrapping up her son. "I didn't think I would be a fan of the swaddling, but the swaddling's pretty amazing," she said.
"It sort of looks a bit like a straightjacket - you're like, 'Is this child abuse?' - but for some reason they just love it."
Theron has been romantically linked to Keanu Reeves and Ryan Reynolds since her split from long-term partner Stuart Townsend in 2010, but is currently believed to be single.
She can be seen next in Ridley Scott's Prometheus, which opens to theatres on June 1 in the UK and June 8 in the US.
> Charlize Theron 'has been trying to adopt for a long time'
> Kristen Stewart's 'Snow White and the Huntsman' - in pictures
Watch the teaser trailer for Prometheus below: