Peter Levene - known as Lord Levene of Portsoken - took over from the newly retired Sax Riley. He is the first chairman in the market's 314-year history to be selected from outside Lloyd's.
Investors in Lloyd's voted in September to abandon long-held practices in the hope of pulling in more business and limiting catastrophic losses.
Key changes include transforming Lloyd's into a franchise network, adopting a system of annual accounting and stopping new individual investors, or "Names," from accepting unlimited liability when they underwrite policies.
Levene said 2003 would be a year of transition as Lloyd's introduces the franchise system and accounting changes.
"By 2004, I expect to see a stronger, more disciplined Lloyds which can be compared favourably with the insurance industry worldwide in terms of its transparency and its efficiency," he said.
"Beyond that, the goal is profitability that is sustainable in the long term. Its a goal I'm committed to achieve."
The goal is to put Lloyd's on a better footing with other insurance companies so that investors and clients can compare them more easily. By doing so, Lloyd's hopes to claw back some of the market share it has lost to more aggressive competitors.
Lloyd's is not a company, but a market comprising 88 syndicates that underwrite insurance. It claims to be the world's second-largest commercial insurer and the seventh-largest reinsurer.
Although Levene has no specific experience in the insurance industry, he built a successful career in business and as a government adviser.
He joined United Scientific Holdings, a defense contractor, and rose to become chairman, before becoming a government adviser on defense. He later headed London's Docklands Light Railway and the city's ambitious Canary Wharf property development. He also served as Lord Mayor of the City of London - the top official in the capital's financial district - and is currently vice chairman of Deutsche Bank AG London. -Sapa-AP