"Although we are closing the appeal, the Full Stop campaign, which is an aspiration to end child cruelty over a generation, is ongoing, and we will continue to fundraise for it," said a spokesman for the NSPCC.
The announcement was made at an event at the charity's Maya Angelou Centre in north London, which was attended by the Prime Minister and the Duke of York, who both launched the appeal in 1999.
The charity said the campaign had allowed it to increase its annual spending on work to end child cruelty to a record level of £92.3m last year.
The extra funding had helped it increase its number of projects from 156 to 180, and to treble the number of children and families receiving in-depth support each year to 21,000. A total of £84.5m was spent on children's services such as its helpline.