"Joni has been hospitalized. We are awaiting official word on her condition and will post it here as soon as we know," the statement read.
An identical message was also posted to her Facebook and Twitter pages shortly before 11 p.m. ET.
Los Angeles fire officials say paramedics answered an afternoon 911 call in Bel Air, where Mitchell lives, and took a patient to the hospital. But they could not verify her identity.
The 71-year-old singer-songwriter told Billboard magazine in December that she has a rare skin condition, Morgellons disease, which prevents her from performing. Still, she released a career-spanning four-disc box set last year and appeared at Clive Davis' annual pre-Grammy party in February.
Mitchell has received eight Grammy Awards, including a lifetime achievement award in 2002. She was inducted into the Rock and Roll Hall of Fame in 1997.
Mitchell, who was born in Fort Macleod, Alta., is also a member of the Canadian Music Hall of Fame and the Canadian Songwriters Hall of Fame.
She has a star on Canada's Walk of Fame in Toronto and a commemorative stamp, and is a companion of the Order of Canada.