In the eparchy of Idukki, there are 18 religious houses for men, belonging to different congregations and 45 priests are engaged in various ministries. There are 124 religious houses of women in the eparchy, belonging to different congregations. 747 religious sisters work in the diocese.

All the religious congregations, both men and women, are actively engaged in the development of high ranges, especially through educational, health care, social service, and pastoral activities. Almost every parish has a convent, where the nuns are engaged in pastoral and educational activities. They teach in the schools, and are engaged in formation of the children and youth in faith and morals. They are a major source of inspiration in the promotion of priestly and religious vocations from this region.  There are prestigious educational institutions run by religious in the diocese. They run hospitals, dispensaries and clinics in the backward places of the diocese, where there are no other medical facilities in emergency needs.

They take care of the abandoned old people and the orphans and economically backward children. Boarding homes and Hostels run by the congregations facilitate the education of children, especially the girls.  

In parishes the religious nuns render their selfless service to animate apostolate among different age groups. They often visit houses, especially the sick and old people and console them. By conducting Home Mission programmes and organizing the activities of various pious associations they help the spiritual growth in the parishes.