The Los Angeles-based company said a reorganisation plan would allow it to reduce its debt from $372m (£226m) to $50m, while eliminating all of its existing preferred stock and common equity.
The company said it had run into financial difficulties because of the downturn in the tech economy and the aftershocks from the terrorist attacks in September 2001.
Key3Media said it would continue its business operations and will retain its existing management team throughout the reorganisation.
The trade show company said its shows and conferences will take place as scheduled, including Comdex Fall, scheduled for 15 to 20 November in Las Vegas; NetWorld+Interop, from 27 April 27 to 2 May and JavaOne San Francisco, from 9 to 13 June.
Just a day after Key3Media's bankruptcy filing, rival company Jupitermedia announced that it would hold its own autumn IT show in Las Vegas at the same time as Comdex.
Jupitermedia chairman and chief executive officer Alan Meckler said his company's new show is being planned because Key3Media's bankruptcy leaves question marks about the future.