The 42-year-old Pitch Perfect alum announced her pregnancy via surrogate on Instagram on Monday.
"Beyond proud to announce the birth of my first child, Royce Lillian, born this past week via surrogate," she wrote at the start of the touching caption.
Wilson continued, "I am prepared to live in luxury little Roycie with all of my affection. I'm learning quickly... Respect to all the mothers out there! I'm honoured to be a member of your organisation. 💗💗💗"
Wilson made her romantic relationship with fashion and jewellery designer Ramona Agruma public on June 9 with a sweet Instagram photo of the two.
"I assumed I was looking for a Disney Prince... But perhaps what I really needed all along was a Disney Princess #loveislove, "written the actress
"It's a very serious relationship, and they're extremely happy together," a source told PEOPLE at the time. "It's been really cool for Rebel's friends to see her so comfortable with someone."
Wilson told PEOPLE in May that her desire to become a mother influenced her decision to embark on her "year of health" in 2020.
"I think that going through the process of finding more self-worth elevates what you want in a partner, so it's great to have someone who feels like an equal partner and be in a healthy relationship," Wilson continued.