Plans to reinvent the BBC “for a new generation” and combat competition from media giants such as Amazon and Netflix are due to be unveiled.
The corporation will reveal its plans later, which will include “the biggest investment in children’s services in a generation”.
An additional £34m will be invested across the three years to 2019-20.
A BBC source says it “needs to respond” to the way children and young people currently watch programmes.
The new investment, delivered following savings made across the BBC, will see the budget for children’s programming reach £124.4m by 2019-20, up from the current figure of £110m.
In three years, £31.4m will be spent online, on content that will include video, live online programme extensions, blogs, vlogs, podcasts, quizzes, guides, games and apps.
By David Sillito, media and arts correspondent
Over the last six years, children’s TV viewing has dropped by more than a quarter.
Youngsters now spend more time online than they do in front of the television, around 15 hours a week. Even pre-schoolers spend more than eight hours a week online, according to Ofcom.
Naturally then, the CBBC channel aimed at six to 12-year-olds has seen a drop in its audience, and increasingly children are choosing to use the BBC’s iPlayer.
Viewing habits are changing, but so too is the content they are watching. Shorter video clips, interactive content and games are all going to increase.
The setting for all of this is a long-term decline in spending on British children’s programmes by other broadcasters – ITV’s programming went from 424 hours in 1998 to 64 in 2013 – and the dominance of US programming.
This will only increase in an online world dominated by the tech giants. Children’s culture is being shaped by firms based on the west coast of America.
BBC director general Tony Hall and BBC chairman Sir David Clementi are publishing the BBC’s first Annual Plan, which will set out the BBC’s ambition for the coming year.
This will explain how the BBC is aiming to tackle such challenges as “fake news” and children’s radically different media choices.
It will also show how the corporation is “going to serve the needs of the nations and regions of the UK,” along with setting “the highest ambition for diversity”.
A BBC source said Lord Hall has “set a clear challenge – to reinvent the BBC for a new generation”.
“The way children and young people are watching and consuming programmes and other content is changing fast, and the BBC needs to respond. This investment will mean we can reinvent how we serve our youngest audience in the years ahead, while continuing to produce outstanding programmes on CBeebies and CBBC.
“Investment in British content – particularly for the young – is vital, unless we want more of our culture shaped and defined by the rise of West Coast American companies.”
The source also said that the BBC is exploring how new technologies can enhance how children and adults discover new content.