The combined organization will have a market cap of "approximately $10 billion and enterprise value of approximately $15 billion," according to a statement from the companies.
The deal is expected to close by the end of 2016, and Envision shareholders will receive 53 percent of the new company, Envision Healthcare Corporation, while AmSurg will get 47 percent.
"This merger will create a national platform with a highly differentiated suite of solutions. It will significantly increase our ability to empower physicians and expand our client relationships," said Christopher Holden, who will serve at the President and CEO of the newly combined combined company.
AmSurg shares gained 1 percent Thursday. Envision shares are slightly lower this year.