She went far away from materialist life and began leading the life of an ascetic. She came to live in Mahatma Gandhi's Ashram in the year 1934. She also raised her voice against inhuman acts like ill treatment of Harijans.

As a Gandhian
She became an active member of Indian National Congress. She was involved in almost all the activities and movements that were launched by Gandhiji for the wellbeing of people. She became one of the most dedicated disciples of Mahatma Gandhi. She sincerely followed the teachings and principles of Bapu. This explains the reason why she was also addressed as a Gandhian. During the Dandi March, she was along with Gandhiji. It is during this movement that, she was imprisoned by the British Raj authorities.

Post-independence
After the Independence of India, Rajkumari Amrit Kaur joined the Jawaharlal Nehru's first Cabinet. She was the first woman to hold a cabinet position. She was made the incharge of Ministry of Health. She was the only Christian in the cabinet of India. In the year 1950, she was elected for the post of President of the World Health Assembly.

She played a pivotal role in the task of conceptualizing and laying the foundation for the establishment of the All India Institute of Medical Sciences in New Delhi. For this, she secured aid from different countries like New Zealand, West Germany etc. She also provided assistance to a rehabilitation centre. She and her brother even donated their ancestral property that was made the holiday home for the staff of the institute.

She served as the Chairperson of the Indian Red Cross society for a long period of fourteen years. She made an immense contribution towards the development of the tribal groups of India. She held the position of health minister till 1957. Thereafter, she took retirement from the ministerial activities, but still remained a part of the Rajya Sabha. Till she was alive, she held the presidency position of AIMS and the Tuberculosis Association. She also served as the chairperson of St. John's Ambulance Corps. This great soul departed for heaven on the 2nd October in the year 1964.