Metro Bank, which in July 2010 became the first new bank on the UK high street in over 100 years, said it had raised 126m pounds to fund expansion plans.
The bank currently has 12 branches in Greater London but plans to have 200 open in the area by 2020.
Chief Executive Craig Donaldson said demand for the share placement reflected Metro Bank's "unprecedented success in the market".
Subscribe to MoneyWeek
Subscribe to MoneyWeek today and get your first six magazine issues absolutely FREE
"We have ambitious expansion plans, and customer reaction to the Metro Bank model means that we are confident in achieving our ambitions," he said.
"Londoners are flocking to us to open accounts and we've been blown away by local reaction to our style of community banking."
New branches that will be funded by the capital include Brighton, Reading, Hemel Hempstead, Romford, Staines and Epsom, the firm said.
Who is the richest person in the world?
The top five richest people in the world have a combined net worth of $825 billion. Who takes the crown for the richest person in the world?
By Vaishali Varu Published
Top 10 stocks with highest growth over past decade - from Nvidia, Microsoft to Netflix, which companies made you the most money?
We reveal the 10 global companies with the biggest returns since 2013. One firm has posted an astonishing 9,870% return, meaning a £1,000 investment would now be worth almost £82,000.
By Ruth Emery Published