Manager Craig Wyckoff says Kelly died on Wednesday at a Los Angeles addiction treatment facility she had entered early this week.
No official cause of death was disclosed.
Kelly portrayed Laurie Forman, sister of Topher Grace's lead character Eric, on the Fox series. It concluded in 2006.
Unlike some of her co-stars - Grace, Ashton Kutcher and Laura Prepon - Kelly fell out of the spotlight after appearing on the sitcom until she started making headlines for personal troubles.
She was arrested in November along with husband Robert Joseph Gilliam in connection with a disturbance at their home in North Carolina.
In June, she was arrested on suspicion of drunken driving after her car stalled in California.
TMZ has further details about her death - watch here:
24.com publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.
Disney Junior (DStv 309) has added top kids TV hits The Adventures of the Gummi Bears and DuckTales to its schedule! Read More »
While plotted, outlined and written for October, the ongoing stories of the characters of SABC1's Generations was never filmed following the firing of the principal cast. Read More »
A quick quickie!
Ready for the Daisies!
Sunnies and beer!
Rocking the Daisies!
Cape TownCommunicate Cape Town ITR25 000 - R30 000 Per Month
Cape TownCommunicate Cape Town ITR35 000 Per Month
HousesR 1 200 000
Apartments / FlatsR 1 095 000
HousesR 4 500 000