Momentum Kids says it will provide childcare to facilitate "political engagement" for single parents.
It will also include "fun, engaging and child-friendly" political activity for youngsters.
Momentum was formed from Mr Corbyn's successful 2015 leadership campaign and is attempting to get him re-elected over Owen Smith on Saturday.
The group aims to create a "mass movement for real transformative change" and says it is committed to securing general election success for Labour.
But Mr Corbyn's critics say it is being used to take over the party and force out MPs who do not want him as leader.
The group is holding a four-day festival next week in Liverpool, where Labour is holding its annual conference.
The World Transformed event will include a creche to encourage parents and carers who would otherwise struggle to attend, organisers say.
There will also be storytelling and workshops on campaigning aimed at young people.
Organisers of Momentum Kids, which hopes to expand across the group's 150 local branches, said it would "create a space for questioning, curious children where we can listen to them and give them a voice".
They also said women were often "shut out of many political spaces" because they do a "disproportionate amount of caring work".
Mr Corbyn recently said companies that encourage after-work drinking were guilty of discrimination against women, "who want to obviously look after the children that they've got".
Children's author Alan Gibbons said: "As young people grow, they need stories, poems, songs, drama and play to develop as complete human beings. An education system that treats them only as future productive drones develops only part of their personality."
His leadership has divided Labour, with most MPs wanting him replaced.
Mr Corbyn has promised to "reach out" to MPs if he is re-elected, but one of his predecessors, Lord Kinnock, said he doubted whether he would see another Labour government in his lifetime if there was another Corbyn victory.
The Jeremy Corbyn-backing Momentum group is launching an initiative aimed at children and their parents.