The `Halo` singer - who is married to hip-hop superstar Jay-Z - was said to be shocked when she discovered she was expecting, but is now thrilled with the news.
A source told Us Weekly magazine: "B was shocked. She loves kids, but she wasn`t ready to be a mother just yet. She really wanted to get her album done and tour the world again."
Another insider added: "She now knows this is a gift from God and she`s so happy."
Friends of the couple - who married in 2008 - have expressed their delight at the news, saying they will make wonderful parents.
Record executive Kevin Liles - a close friend of Jay-Z - said: "Jay has been all about family since I met him, and he`s always going to be. I wish them the best."
Beyonce-s sister Solange added:
"She`s got the most beautiful heart. She`ll be a great mom."
In 2008, Beyonce said she "isn`t ready" to have children.
The 29-year-old beauty revealed: "I know I want kids but I have never been a girl who sees a baby and goes, `Oh! I want one!` But when I do eventually have a child, I can only pray he is as amazing as my nephew Jules. He`s just the best. He is also a lot of work!
"I`ve seen the reality of having a kid and I know I`m not quite ready for it yet."