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.
MultiChoice upgraded e.tv’s signal to HD quality on DStv and the channel’s local weekday soaps will be added to the DStv Catch Up. Read More »
M-Net and its Magic in Motion Academy has become embroiled in a row about race with trade union Solidary. Read More »
Scientists and researchers believe that almost five million tons of plastic is dumped in the oceans every year and it’s affecting our food.
Cape Town CBD
HousesR 3 200 000
HousesR 2 795 000
TownhousesR 1 250 000