ITV stripped away much of its peaktime schedule for special programmes containing no advertising breaks.
It broadcast a documentary September Mourning about how the bereaved British families are coping, which ran for the full 66 minutes from 10pm.
Two ITV News specials covering the memorial services were also transmitted without ad breaks.
A spokesperson for ITV said that the airtime would be redistributed according to the Independent Television Commission regulations and that it would not have an adverse effect on advertising revenues.
Channel 5 did not cut its commercial airtime but ran a two-minute silence at 1.45pm, the time the first plane hit the south tower of the World Trade Centre. Two shows - The Wright Stuff and Open House with Gloria Hunniford - focused on the attacks.
GMTV ran programming with reports from New York, Kabul, Baghdad and London.
Its commercial airtime was unaffected by its coverage.
Channel 4 showed a series of documentaries in the run-up to the anniversary, concluding with a documentary on the fliers posted after the collapse of the World Trade Center.
All BBC services observed a minute's silence including the UKTV channels, which took the live BBC 1 feed from Ground Zero.
US TV was virtually advertising-free with the exception of children's programming. The giant screens in New York's Times Square were also kept free of commercials.
The events follow a prediction from JP Morgan that US adspend could rise by 2 per cent this year, with TV and radio the strongest performers.