RCP Singh’s career began as the Indian Revenue Service Officer (IRS) and later in 1979, he started working as a member of the Indian Administrative Service (IAS) which is considered to be one of the most esteemed and highest positions of power in India. He worked as a Principal Secretary to Nitish Kumar, the Chief Minister of Bihar, before venturing into politics himself.

Months before he retired from the Administrative Services, he quit his job and stepped foot in politics. This marked a new chapter in his career, as he wanted to serve the people of Bihar and advocate for their rights. Singh joined the Janata Dal (United) and his years of administrative experience proved him to resume a prominent role within the party from the get-go. He served as a Member of Parliament in the Rajya Sabha representing Bihar from 2010-2022. One of the major events of Singh’s political career was his appointment as the national president of the JD(U). His position in the party has proved influential in the party’s continuous success in Bihar. 

In August of 2022, however, Singh resigned from his position at the Janata Dal (United) party citing personal reasons which were a result of a falling out with former close friend Nitish Kumar. His resignation sparked speculation about political realignment in Bihar. After his departure, Singh made headlines after announcing his new affiliation with the opposition party Bhartiya Janata Party (BJP). 

During his tenure in the Rajya Sabha, Singh served on several Parliamentary committees including the Committee on Subordinate Legislation, the Committee on Petitions, and the Committee on Government Assurances. During his time as the Minister of State for Steel in the Union Council of Ministers, he focused on promoting the growth and development of the steel industry in India and the promotion of environmentally friendly practices.