The company pleaded guilty to breaching s 3(1) of the Health and Safety at Work Act at Luton Crown Court on 13 March.
A Central Bedfordshire Council investigation into the incident at Woburn Forest Village on 22 October 2015 found that a Center Parcs employee was supervising seven children in an organised tree climb.
The employee had been tasked with providing a safety talk, fitting a harness on each child, and clipping each child to the fall-arrest system before the activity started.
One of the children, aged eight, started to climb the tree without being clipped to the fall arrest system. When she had climbed up to about 3 m, she fell and broke her wrist.
Councillor Ian Dalgarno, executive member for community services at the council, said: "Our investigations found inadequate risk assessments in place, an unsafe system of work, and inadequate monitoring to ensure that the tree climbing activity was safe."
A spokesperson for Center Parcs said the company "accepts full responsibility".
In a statement reported by the Nottingham Post, the spokesperson said: "We take the health, safety and wellbeing of our guests extremely seriously, and from the outset have co-operated fully and proactively with the investigation."
Center Parcs said that it had reviewed and amended its operating procedures in relation to tree climbing following the incident.
Woburn Forest Village is a separate legal entity to the other Center Parcs companies. However, its safety and health is managed by Center Parcs UK (which is owned by Blackstone Group) and it has the same board of directors as the other Center Parcs UK divisions.
In addition to the fine, the company has to pay £14,000 in costs.
