Justices Singh and Nagappan were the Chief Justices of Allahabad High Court and Orissa High Court respectively.
The sanctioned strength of judges in the apex court is 31 including the CJI.
The two judges were elevated to apex court and were administered the oath of office and secrecy by CJI Sathasivam.
Singh, 62, hails from Bihar and took charge of Acting Chief Justice of Allahabad High Court on November 20, 2012. However, he was elevated as Chief Justice on February 4.
Justice Nagappan, 62, hails from Karur district in Tamil Nadu.