Ranjan, who hails from Samastipur in Bihar, completed his schooling in the State before moving to Delhi for his legal education. He completed his LLB in 2005 and began his legal practice under the guidance of former Union Law Minister and advocate Ram Jethmalani.
Ranjan has been practising before the Supreme Court for more than 20 years and has handled matters involving civil and criminal law, constitutional law, service law, land acquisition, intellectual property rights, companies, taxation, work contracts and arbitration.