Corporate lawyers, accountants, traders and bankers are taking major pay cuts, relying on an annual wage of about £22,500 pro rata while they retrain for work in social enterprise through a programme called On Purpose.
The programme's so-called "associates" then take on placements at organisations like the prisoner-run Bad Boys' Bakery, social investment group Big Society Capital and food distributors FoodCycle.
On Purpose chief executive Tom Rippin told the Press Association that they are drawing in young City workers who are starting to question their career trajectories.
"A lot of people say 'I just didn't feel like I was doing anything very meaningful, I was looking for meaning, I wanted to have some purpose beyond just making some rich people richer or creating some sort of profits for some shareholders'," Rippin said.
Over 200 people have gone through the one-year programme since it was launched 2010, with the latest cohort initiated earlier this month.
Thirty-five-year-old Georgina Smee joined On Purpose earlier this year. The former corporate lawyer had been promoted and offered a secondment to New York after eight years at her firm, but quit after realising that she was not willing to be on-call 24/7 and glued to her BlackBerry.
"I think the priorities are so skewed in corporate law firms and the expectations are extraordinary," she said.
But moving from a £100,000 salary has not come without challenges. Ms Smee said she now bikes to work since she can no longer afford public transport.
"It's a huge salary cut but that's just not what it's about. For me, life is too short to do work that you don't care about. And I want enough money but I don't need loads of money," she explained.
Ms Smee is on a six-month placement with Big Society Capital, after having stepped in as acting chief operating officer during her first placement with FoodCycle earlier this year.
"Sometimes when you're in the thick of it you don't step back and think about what's really important," she added.
Rippin said very few big corporates actually started off with the sole mission of making money, and many have lost their moral compass.
"You start off being a grocer, you're about providing good quality food to your neighbourhood. You're creating sports stores, you have some sort of dream about helping athletes, that sort of stuff.
"And yet, (for) a lot of, especially big publicly-listed companies, a lot of that seems to get lost. People can't see how they are contributing to a broader purpose that is somehow beyond the economic."
But London is not the only city seeing a corporate exodus. On Purpose opened a programme in Paris last spring, and started its third chapter in Berlin back in February.
Rippin said that while the capital and state models vary from country to country, On Purpose is clocking some trends.
"The thing that is interesting to us... is that we find the similar kind of desires, motivations, wanting to change, among the professionals... (and) across those cities," Rippin explained.