The company, which is also behind Quo Vadis and El Pastor, hit its goal within two hours of its Crowdcube page going live to pre-sale subscribers.
Supporters and interested investors could opt-in to get early access to the crowdfunding page ahead of its public launch today (14 June).
At the time of writing the group has raised £1.6m from 360 investors to launch its biggest Barrafina yet at the Coal Drops Yard development in King’s Cross.
The restaurant will open in October and feature a 34-cover bar, 20-cover private dining room and 60-cover weatherproof terrace.
Harts Group will continue to raise funds for the remaining 30 days of its pitch, which will be capped at £2.5m and invested in the new site.
Writing on its Crowdcube page the company, which is valued at £16m, says it plans to expand its business worldwide beyond 2020 in to locations such as Ibiza, New York and other major cities.
“We were confident in our offer but you helping us to achieve our target so fast has blown us away and we are delighted to have you all on board,” Harts Group wrote.
“We cannot wait to make Barrafina Kings Cross into a beautiful marble-barred and leather-seated reality and we hope to raise a glass with each of you at any of the Barrafinas or Quo Vadis soon.”
Harts Group is also planning to open two new concepts at Coal Drops Yard, Casa Pastor - described as a 160-cover ‘Mexican big sister’ to Borough Market's El Pastor - and 79-cover wine bar The Drop.
A former Victorian coal store, Coal Drops Yard is being redeveloped in to a restaurant and retail space. It will open as a whole this autumn and is expected to welcome 20m visitors a year.
Barrafina Dean Street holds a Michelin star, while its sister Adelaide Street site was named National Restaurant of the Year at the 2015 National Restaurant Awards.