Mark Carney told the Guardian the financial sector could be worth 20 times the UK's economic output in 25 years.
He said: "If the UK financial system thrives in a post-Brexit world... it will be 15 to 20 times GDP in another quarter of century.
"Well then you really have to hold your nerve and keep the focus."
Carney was speaking to the Guardian to mark the 10th anniversary of the start of the global financial crisis in August 2007.
He said the UK could not return to the pre-crisis light-touch regulation in order to attract business after leaving the EU.
The governor has previously said the UK after Brexit could be the "investment banker for Europe".
He said: "We have a financial system that is [now] ten times the size of this economy… It brings many strengths, it brings a million jobs, it pays 11% of tax revenue, it is the biggest export industry by some token… all good things.
"But it's risky."
"We have a view… that post-Brexit the level of regulation will be at least as high as it currently is and that's a level that in many cases substantially exceeds international norms.
"The problem you have is that the same issues re-emerge under different labels… and the progress that's been made… is gradually chipped away."
Mr Carney's comments come as US regulators begin formal proceedings to loosen regulations brought in after the financial crisis to curb the way banks took high-risk bets on the financial markets.

In 14 previous Games, GB has never finished lower than fifth in the medal table, and has come second seven times.
But London 2012's third-place finish ended a run of three second places and Rio 2016 is set to be more challenging.
"It's getting harder and harder because other nations are picking up on this and investing more money," said GB Wheelchair Tennis' Geraint Richards.
"There will be a time when we can't keep increasing the medal tally but we can stay at the top end of the table."
Richards, head of disability player performance at the Tennis Foundation, said he is optimistic about star performer Jordanne Whiley's chance of gold in the singles and doubles events in Rio, but was reluctant to put too much expectation on the 23-year-old in a sport that gets "tougher and tougher".
It is a similar story for his counterpart at the British para-swimming team, Chris Furber.
The former head coach of the successful British para-cycling team, Furber has overhauled the swimming set-up: bringing in new coaches, centralising the team in Manchester and investing in infrastructure.
He is confident the team will "contribute a hefty number of medals" to the target of 121 - one more than was won in 2012 - that is the "aspirational goal" for the agency that funds Olympic and Paralympic sport, UK Sport.
However, he said medal tallies are "really hard to predict", pointing to the London Games as an example.
"It's not the same as Olympic sport where you get a level of performance over the four years," said Furber.
"China turned up with a very strong team off the back of their home Games, Russia and Ukraine had heavily invested and Brazil were looking to their home Games, so London was challenging and Rio will be no different."
"Our entire four-year cycle has been about producing a lifetime-best performances under the greatest pressure."
Tim Hollingsworth, the British Paralympic Association's chief executive, has welcomed rising standards, even if it does make it harder for the British team to deliver medals.
"The standard of competition globally in the Paralympic movement is changing rapidly," said Hollingsworth.
"It's going to make the winning of the medals even tougher but we're on the cusp of something great with the Paralympics - London was tremendous, we're very keen to see that go forward."
The governor of the Bank of England has said the banking sector could double in size but still needs tough regulation.
[NEXT_CONCEPT]
British Paralympic leaders say Britain can continue to deliver medals despite increased global competition.