The Brigg youngster will represent Great Britain in the Children and Junior European Championships in Samorin, Slovakia.
The competition takes place between August 8 and 13 at the x-bionic equestor sphere.
Holly, 14, will compete with Golly Girl, an 11-year-old chestnut mare owned by Barrie Truelove.
The Children Team medals will be decided on August 10 and the youngsters will then compete for their individual medals on August 12.
The Chef d’Equipes accompanying the teams will be Tony Newbery and Clare Whitaker.