Altman will remain chairman, the top U.S. merger advisory boutique said.
Schlosstein has also become a partner in Evercore and bought $15 million of its equity, Evercore said in a statement.
The company was not immediately available for comments outside regular business hours.
Evercore, which is advising Wyeth (WYE.N) on its $68 billion deal with Pfizer Inc (PFE.N), posted a 19 percent jump in advisory revenue for the first quarter in April, but said investment management revenue slumped 75 percent for the period.
Schlosstein worked for Lehman Brothers and co-founded BlackRock, now the biggest publicly traded U.S. asset manager, in 1988.
Amid one of the worst financial meltdowns, boutique firms that focus mainly on providing merger advice — such as Lazard Ltd (LAZ.N) and Evercore Partners — are seen as well positioned to remain independent and profitable.
Shares of Evercore closed at $16.85 Thursday on the New York Stock Exchange. (Reporting by Anurag Kotoky in Bangalore; Editing by Deepak Kannan)