'Halo' singer Beyoncé posted a brief but heartfelt message on her official website on Monday evening (17 June), accompanied by a picture of Kim and Kanye gazing at each other.
Beyoncé, who has a one-year-old daughter, Blue Ivy, with her rapper husband Jay-Z, wrote: "Congratulations Kim & Kanye, enjoy this beautiful moment together."
Keeping Up With The Kardashians star Kim gave birth to the couple's first child, a daughter, on Saturday, 15 June, but so far no further details about the new arrival, including a name, have been released. It's thought her due date wasn't until next month.
Normally prolific tweeter Kim has remained silent on her social networking accounts since the weekend. Neither she nor Kanye have issued any public statement on the birth.
Beyoncé's public message of support will help brush away those persistent rumours that she's not Kim's biggest fan.
The women got to know each other through their significant others, and were spotted spending time together during the 'Watch The Throne' tour last year. Kim also flew to London to watch Beyoncé in concert earlier this year.
They also met up at the glitzy Met Ball in New York in May.