"Future Zahir Wilburn 9lbs 10oz May 19 2014" Ciara tweeted to her five million fans on Tuesday afternoon, with a link to a snap of the little one's arm on Instagram.
According to the New York Post's Page Six column, the singer gave birth to her son in the early hours of Monday morning in Los Angeles.
The newborn is the Speechless singer's first child, and her rapper fiancé Future's fourth.
Speaking to Us Weekly when she was pregnant, Ciara said of choosing her child's name: "I went with what felt right in my soul and my gut. I didn't second guess it."
She also said that being pregnant was wonderful.
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"I didn't even know what to expect, but it's been a very easy process. And it's been so much fun," Ciara continued.
"Honestly, it's been the coolest experience in my life. Being able to know that I can do that is such a blessing. I'm literally obsessed with kids, so I'm excited about being able to have my own to obsess over."
Ciara got engaged to music producer Future – real name Nayvadius Cash – in October last year.
The rapper proposed on Ciara's 28 October birthday, presenting her with a huge diamond ring which has drawn comparisons with the sparkler with which Kris Humpries presented Kim Kardashian.
Ciara, who recently shared this snap of her nursery, and her fiancé Future welcomed their baby in Los Angeles on Monday
Ciara shared the exciting news of her pregnancy in January during a US TV appearance.
Asked by The View host Barbara Walters if she had "anything to confirm", referring to the months of pregnancy rumours which had surrounded her, Ciara happily revealed her burgeoning baby bump to the delight of the audience.