The rapper announced at a concert on Sunday night that his girlfriend is pregnant.
He told the crowd of more than 5,000 at Revel Resort’s Ovation Hall in song form: “Now you having my baby.”
The crowd roared.
And so did people on the internet.
The news instantly went viral on Twitter and Facebook, with thousands posting and commenting on the expecting couple.
Most of the Kardashian clan also tweeted about the news, including Kim’s sisters and mother.
Kourtney Kardashian wrote: “Been wanting to shout from the rooftops with joy and now I can!
“Another angel to welcome to our family. Overwhelmed with excitement!”
West, 35, also told concertgoers to congratulate his “baby mom” and that this was the “most amazing thing.”
Representatives for West and Kardashian, 32, were unavailable to comment about the pregnancy.
The rapper and reality TV star went public as a couple in March.
Kardashian married NBA player Kris Humphries in Aug 2011 and their divorce is not finalised.
West’s Sunday night show was his third consecutive performance at Revel. He took the stage for nearly two hours, performing hits like Good Life, Jesus Walks and Clique in an all-white ensemble with two band mates.
Kardashian, 32, who rose to fame five years ago for her appearances in reality TV show Keeping Up with the Kardashians, was the most-searched person on the Yahoo website in 2012.
She married Humphries in Aug 2011, in a lavish, made-for-TV wedding, but the couple divorced just 72 days later.