Willkie Farr & Gallagher on Tuesday said it hired McLean in Houston, where she will be a partner in Willkie's private equity practice.
McLean "brings significant dealmaking experience to our global energy team in Texas and across the U.S. and Europe," Willkie chairman Thomas Cerabino said in a statement.
A Shearman spokesperson said the firm thanks McLean for her contribution and wished her well.
The firm is in the process of implementing its merger with Allen & Overy to create a firm with nearly 4,000 lawyers, including about 800 partners, across 48 global offices. The firms said in October that more than 99% of each partnership voted in favor of the deal.
The merger is expected to be finalized in May, and the firms will become Allen Overy Shearman Sterling, or A&O Shearman for short.
"Upon completion of the transaction, A&O Shearman will have a powerhouse private equity and energy offering," a Shearman spokesperson said Tuesday.