The woman made a complaint to her Police College supervisors and the recruit who allegedly touched her was stood down.
A spokesperson for Police National Headquarters confirmed a Police College recruit has been charged with indecent assault and will appear in the Porirua District Court this month.
She could not comment further as the matter was before the courts.
Police Association president Chris Cahill confirmed the union was involved but declined to comment.
The alleged grope of an undressed female recruit is understood to be the most serious in a recent string of incidents Police College leaders have dealt with.
Last month, the Herald revealed a police recruit was suspended the night before his graduation after he allegedly made comments about snorting cocaine with a fellow trainee.
The alleged comments about wanting to consume the Class-A drug were made in front of members of their training wing, who reported him to their supervisors at the Police College in Porirua.
Police officers searched the rooms of the recruit, as well as the wingmate he name-dropped in the alleged drug talk, although no cocaine was found.
Despite the lack of evidence, police bosses decided to investigate further and stopped the recruit who made the alleged drug remarks from graduating with his wing the next day.
A police spokesperson confirmed the recruit's alleged comments were being investigated but declined to comment further.
"New Zealand Police has the same privacy obligations as any other employer and as such is not in a position to provide any further detail at this time."
In recent years, police recruits have been stood down because of alleged links to organised crime. But these recent incidents of potentially criminal behaviour come shortly after the culture and training at Police College was put through an independent review commissioned by Deputy Commissioner Tania Kura.
The report is not publicly available but Kura recently said the review found areas to improve including the academic framework, the type of staff employed as trainers, and its connection to "real world" policing.
A new director of training at Police College was appointed in February, the highly rated Superintendent Warwick Morehu, and a second review into the entire training process is now underway.