"Yes, he is the man who was the father to River, who we lost last year, at 11 months old," Sharon clarified.
Sharon went on to thank her fans for their support during her time of immense grief.
TIMELESS BEAUTY AND ‘BASIC INSTINCT’ STAR SHARON STONE STUNS IN FILMS AND ON THE RED CARPET
Sharon Stone paid tribute to her brother on Instagram. (Instagram: Sharon Stone)
"Like any family, we thank you for your love and support in this time of immeasurable grief, and we appreciate all of your condolences," Sharon continued, through tears. "We've had a tremendous amount of loss in these last couple of years, as so many of you also have... I thank you very much for the love and support you're showing us."
The "Basic Instinct" star also shared some throwback photos of her brother.
Many celebrities shared messages to Sharon in the comments of her post including John Travolta.
"Dearest Sharon, I’m so sorry for your loss. I do understand very well what you’re going through," he wrote. "With love."
Sharon Stone confirmed Patrick Stone was the father of River, the nephew she lost in 2021. (Gisela Schober/Getty Images)
Sharon Stone has three children of her own. (Getty Images)
Jeremy Renner also shared support writing, "Bless you."
"Godspeed Patrick, and deepest condolences to you and your entire family," Hilary Swank added.
Orlando Bloom wrote, "Love and prayers."
Patrick lost his 11-month-old son in 2021 after the child suffered total organ failure. Sharon shared the loss on social media at the time by posting a one-minute video of River playing and smiling.
Sharon has three kids of her own; Roan, Quinn and Laird.