Erburu became lead director and de facto head in October after Chairman and Chief Executive Jeffrey Greenberg resigned following a bid-rigging lawsuit from the New York Attorney General's Office.
In November, five other inside directors resigned, leaving Marsh Chief Executive Michael Cherkasky and 10 outside directors remaining.
No replacement was immediately named as the lawsuit took precedence. Marsh settled the lawsuit for $850 million at the end of January.
Erburu, 74, joined the board in 1996, the same year he retired as chairman of Times Mirror Co.
New York-based Marsh had assets of $18.34 billion as of Dec. 31.
By: (AP) Marsh & McLennan Cos., the world's largest insurance brokerage, Thursday said it named Robert Erburu as nonexecutive chairman.