E! News reported West announced the pregnancy to fans at his show in Atlantic City, N.J., Sunday night and Kardashian's family confirmed she is 12 weeks pregnant with her first child.
The reaction from family and friends was positive, the entertainment news website said.
"Congrats to Kim and Kanye. Happy for both of them... bit.ly/YE4Uzh," Russell Simmons tweeted.
"Im a happy girl !!!!!!!!! Wowza! Oh BABY BABY BABY," Kris Jenner tweeted.
"Keeping secrets is hard with so many family members! Especially when you are so freaking excited!!!!! LOVE is everything!!!!" wrote Khloe Kardashian Odom wrote.
"Been wanting to shout from the rooftops with joy and now I can! Another angel to welcome to our family. Overwhelmed with excitement!" Kourtney Kardashian gushed on Twitter.
Pregnant Mila Kunis wins 'Best Villain' at MTV Movie Awards
'Happy' fan videos make Pharrell cry [VIDEO]