He would also run the main program for income-based government-subsidized health insurance under the Affordable Care Act, also known as Obamacare.
Collectively these programs provide coverage for almost 172 million people, government data shows.
He could be tasked with overseeing significant cuts to Medicaid as Republicans say they hope to cut federal spending in the program. Republicans in the House of Representatives demand $880 billion in Medicaid savings, which they argue could be achieved by rooting out fraud and abuse. Democrats argue it will result in benefit cuts.
Oz, 64, gained national prominence as a cardiothoracic surgeon and television personality, hosting "The Dr. Oz Show" for over a decade.