Speaking on The Ellen DeGeneres Show, the Snow White and the Huntsman actress revealed that she waited for 24 months before her son Jackson could come into her life in March.
Theron said: "My mum said the most beautiful thing. She said, 'You know, it took me nine months to fall in love with you while you were growing in my stomach, and it took you two years to fall in love with this little baby'.
"It took two years of waiting, and then one day, it's finally there, and it feels exactly how it's supposed to feel. I don't know how to describe it. It just feels right."
Theron also revealed that her pets didn't take long to become attached to the new addition to her family.
The 36-year-old star said of her rescue dogs, a terrier mutt and a pitbull named Blue: "Dogs tend to... it takes them a little bit to really fall madly in love with someone. They know their owner and they'll be friendly, but they won't fall madly in love with just a stranger instantly."
"From the moment this baby came into our home, those two dogs have never been more in love. It's the most beautiful thing I've ever witnessed."
She continued. "The pit woke up with me for every feed, for every change. And whenever the baby would cry, the pit would start crying.
"People keep saying, 'You're a single mum.' I go, 'Actually, I'm not. I got two boys helping me out.'"