It will donate a minimum of £20,000 a year for the next three years to the Children’s Society, which helps disadvantaged children.
This will be instead of funding the Prince’s Foundation for Children and the Arts, whose three-year deal has now expired.
Charlotte Geeves, chief executive of the festival, said: “This tie-up will let festival-goers know that when they come they’ll also be helping some of the most disadvantaged children and young people.
“The power of music and the arts can inspire and help give young carers valuable respite.
“We pride ourselves on supporting local and national charity projects through our grants scheme and are looking forward to working closer with the Children’s Society and the young carers and groups that they support.”
The festival’s pledged money, which will come from the ticket sales, will provide support to thousands of young carers through a national programme offering respite, life skills, advice and confidence-building.
The programme will also campaign to increase recognition and improve help for young carers among schools, doctors and local councils, to prevent children as young as three falling through the gaps in support.
The Children’s Society works directly with carers as young as 10, who take on adult responsibilities, such as managing household finances, administering medication and being an emotional support around the clock.
Matthew Reed, the charity’s chief executive, said: “We are thrilled that Henley Festival has chosen The Children’s Society for this important partnership. “Young carers typically show enormous courage and resilience, but the impact on these children is real.
“It can leave them tired and isolated, struggling to socialise and complete school work on time. Children should not be plugging the gaps and taking on inappropriate caring responsibilities.”
He added: “We will make sure that young carers’ voices are heard, and that their lives are no longer hidden behind closed doors.”
Official statistics estimate that there are 166,000 young carers in the UK, including 1,300 in Oxfordshire. Many are forced to miss out on vital education because of day-to-day responsibilities for emotional, practical or physical care for a parent, sibling or other family member.
The festival’s own trust has previously funded many projects, including the former Henley Festival Orchestra, which is now the Henley Music School, an associated music tuition scheme, and a music therapist for Headway.
This year’s festival will take place from July 6 to 10. The opening night, when Elton John will be the headline act, has already sold out. The performers on the other four nights will be revealed on Thursday.