Action for Kids and four other charities complained that the name change would cause misdirected donations, calls to be made to the wrong phone lines and mail to be sent to the wrong address.
But the Charity Commission has ruled that there is "not a material risk of public confusion" and allowed the name change to go ahead.
NCH first adopted the strapline Action for Children 14 years ago, but abandoned it again six years later.
According to Action for Kids, the change consistently caused confusion, with many donations, including a cheque for £108,000, being sent to the wrong address.
NCH said it had written to Action for Kids about its decision to change its name, but had received no response. Mike Hayes, chief executive of Action For Kids, said NCH had not listened to his charity's continual protests.
He said: "The potential confusion and administrative burden that may be imposed on Action For Kids as a result of this name change is huge. Charities that have similar names and causes may well have their profiles swamped.
"We will continue to monitor and document any confusion caused after the launch of the new name and communicate this to the Charity Commission as appropriate."
A spokeswoman for NCH said she was confident that the charity's mission and new identity were distinct enough for it not to be confused with other organisations.
"We have worked closely with the Charity Commission to ensure that in changing our name we respect the position of other charities that have expressed an interest in what we are doing, and we are committed to continuing these efforts," she said.
"The Charity Commission has made it clear that it is content for us to use the name Action for Children."