The modernization of the 50-year-old constitution was backed by voters in a May referendum and approved by U.K. officials in June.

Under the new charter, McKeeva Bush will serve as the first premier of the three-island British dependency of nearly 50,000 inhabitants and will oversee government business in the territory, one of the world's major tax havens.

"This post is not one of absolute power," Bush said in a statement. "In contrast, it equates to being an engineer first, one selected from amongst equals."

The new constitution limits premiers to two consecutive four-year terms and creates the office of deputy premier.

The Cayman Islands' Bill of Rights will go into effect in November 2012. The government said this extended timeframe was needed to allow officials to complete preparations, such as ensuring that local laws comply with the revised constitution.

The London-appointed governor, Stuart Jack, said Friday's commencement of the new constitution was the "highlight of my four years in the Cayman Islands."

"I am confident that the new constitution will serve well these islands and provide a sound basis for the relationship with the United Kingdom," Jack said.