The UK's banking regulator, the Financial Services Authority (FSA), has been abolished and replaced with two successor organisations.
The changes mark the end of the system set up by the previous Labour government.
From 1 April, the Prudential Regulation Authority (PRA) will ensure the stability of financial services firms and be part of the Bank of England.
The Financial Conduct Authority (FCA) is now the City's behavioural watchdog.
The Bank of England has also gained direct supervision for the whole of the banking system through its powerful Financial Policy Committee (FPC), which can instruct the two new regulators.
Chancellor George Osborne announced the changes back in 2010, aiming to make it clear who is in charge over supervising the financial services sector and avoid a recurrence of failing banks and enormous state-backed bailouts.
The regulator changes see the Bank of England - which gains a new governor, Mark Carney, in July - gain much more control over the functioning of the financial system and are the biggest changes to the central bank since it was given its independence in 1997.
The PRA is headed by the central bank's deputy governor Andrew Bailey, and will regulate around 1,700 financial firms. The FCA is headed by Martin Wheatley, who worked at the FSA and was responsible for the review into the Libor rate-rigging scandal at banks.
The FSA was set up 1997 as part of the so-called tripartite structure whereby banks, insurers, building societies and other such firms were regulated by the FSA, the Treasury and the Bank of England.
Gordon Brown, the then-chancellor, created the FSA following criticism that the Bank of England had failed to sufficiently regulate the UK's financial system.
But the FSA was roundly criticised for failing to spot the lending boom and subsequent bust and for not curbing the risky trading of banks, which ended up seeing banks like Northern Rock, Royal Bank of Scotland and Lloyds all spectacularly collapse and be bailed out by the taxpayer following the global financial crisis in 2008.
As a result, the FPC of the UK central bank was created on an interim basis and has been active since 2011 to identify systemic issues that threaten the whole financial system.
Its existence was formalised in the Financial Services Bill, the parliamentary bill passed earlier this year which overhauled the financial regulatory framework.