Although she's been very involved in the pregnancy, Tina claimed a few weeks ago that she had been kept in the dark over the babies' genders.
The singer gave birth to the twins in a Los Angeles-area hospital some time last week, according to multiple sources.
He used several hashtags, including #beyonce, #jayz and #twins.
The new additions bring the superstar family count to five, as they join the power couple's 5-year-old daughter Blue Ivy.
The "queen of pop"'s father Matthew Knowles, with whom she has had a strained relationship, posted a birthday message to the twins, captioned "They're here!" and signed "Love, Granddad".
Schoolgirl gang-raped, thrown off from running train in Bihar
They threw her out of the train as Kiul Junction, after which she was taken to a medical centre nearby by the locals. She was then taken on-board a train where they raped her again and wounded her private parts.
While the world is waiting for one of Beyonce's stunning announcement Instagram posts confirming this news, fans worldwide can relax a bit, thanks to the deductions made by the singer's greatest fans.
In 2012, the birth of the couple's first child, Blue Ivy, caused a media sensation, leading New York's Lenox Hill Hospital to shut down part of its maternity wing to accommodate music's royal couple.
The image took over the internet, becoming the most-liked Instagram pic of all time with 6 million+ views within 24 hours of its posting.
Beyonce and Jay Z have yet to commented on the big news.
Though Knowles is grandfather to the twins, the 65-year-old found out about Beyonce's pregnancy via social media just like the rest of the world.