The £25m Airlander 10 is being built at Cardington Sheds in Bedfordshire and is due to be launched later this month.
Hybrid Air Vehicles (HAV) said the latest crowdfunding drive had seen some 600 people invest in the project.
A spokesman said: "It's staggering and fantastic, and great to know that the general public is behind us."
The company, which has been raising £4m for its extensive Return to Flight programme both through this scheme and other "high net worth" investors, said it would be allowing further donations for a "limited period".
Investors will get shares in the company.
The Airlander 10 is 302ft (92m) long and has been built in the UK's biggest aircraft hangar.
The US army ran out of money to develop the Airlander 10 as a surveillance machine, so the British aerospace company behind it bought back the rights.
HAV has spent the past nine years developing the prototype, which has been described as the "flying bum" by some on social media.
The firm is hoping to build 12 Airlanders a year by 2018.
Hundreds of people invested £500,000 in less than 10 hours to help get the world's largest aircraft - dubbed the "flying bum" - off the ground.