Holmes, who began the role last week, was previously head of TV and media operations at the BBC, where according to her LinkedIn profile she controlled an annual budget of £30m and was "responsible for strategy and management of the operational and media services required to deliver content to the networked channels, as well as the BBC’s digital platforms and outlets for social media".
Before this she held a number of other BBC roles including producer and developer for factual programming over 12 years.
A Barnardo's press release said Holmes would "help shape the charity’s work across communications and policy, supporting the work Barnardo’s does to transform the lives of thousands of vulnerable children".
Holmes reports to Adam Pemberton, the charity's director of strategy and performance, who joined last month.
Last year 240,000 children and their families were supported by Barnardo’s through 960 services across the UK. Its accounts for the year to 31 March 2015 showed it had 5,500 employees – making it the 11th biggest charity employer in England and Wales according to the Charity Commission – and income of £296m, the 14th highest figure nationally.
Javed Khan, chief executive of the charity, said: "Gill brings great enthusiasm and skills from her time at the BBC and we will look forward to Barnardo’s benefiting from this in the coming years."
Holmes said the new role was "a great opportunity to use my experience to support Barnardo’s work in transforming the lives of the most vulnerable children and young people across the UK".