Marsh will join William Hill later this year, taking over from Ruth Prior whose departure was announced last month.
William Hill has aggressively expanded into the United States, and recently announced a digital partnership with CBS Sports, giving the British betting firm a platform for brand promotion and access to customers of the U.S.-based company.
British betting companies have been pivoting to the United States after the U.S. Supreme Court overturned a federal ban on sports betting, while proposed regulatory curbs in the UK are posing a challenge to gambling firms at home.
Marsh will be tasked with steering the company through regulatory hurdles in its home market as the government seeks to impose further restrictions after cutting the maximum stake allowed on high-speed slot machines to 2 pounds from 100 pounds.
Last month, William Hill said Prior will step down to return to private equity sector and join Element Materials Technology as its chief financial officer.
(Reporting by Tanishaa Nadkar and Samantha Machado in Bengaluru; Editing by Shounak Dasgupta and Sherry Jacob-Phillips)