The new Environment Agency fortifications have strengthened existing embankments, offering residents peace of mind.
Rob Waltham, Conservative councillor for Burringham and Gunness ward, said: "It's really good news.
"We had a few properties flooded in the past and this will help build confidence among local residents.
"People will be more at ease."
The work was completed five weeks ahead of schedule and £500,000 under budget.
Mr Waltham thought residents played a vital role in getting the £1.4 million work done.
"It's a good example of good communication within an area," he said. "Residents were really supportive.
"There was some inconvenience, but we had a public meeting and it all went really well."
A public drop-in session was held last December.
Proposals for the improvements were unveiled, and work to stabilise the embankments began in January.
Innes Thomson, area flood risk manager for the Environment Agency, said: "This is excellent news for residents of Gunness. It is even better news that we have been able to finish the work five weeks ahead of schedule.
"Gunness will now benefit from flood defences that provide a modern standard of flood protection. "However, people living behind defences should remain prepared for flooding, as it is always possible for water to come over the top of a flood defence in an extreme event."
The chance either a river or a tidal flood will affect Gunness within a given year is half of one per cent.
The town was defended by embankments downstream of Gunness Wharf, which date back to the 1930s.
But the new Environment Agency defences will provide better protection when flooding occurs.
A spokesman for the Environment Agency said: "We are now waiting for the flood bank to seed and grass over and then we can reopen it to the public."
The Gunness scheme is one of the first to be completed as a result of the Humber Strategy, a 100-year plan for flood risk management around the estuary.
It is part of a £36 million partnership the Environment Agency has set up with specialist engineering firm Birse Civils and design consultants Halcrow, Black & Veatch and Arup.
It is estimated the first package of flood risk management works will provide protection for more than 40,000 people in North Lincolnshire and East Yorkshire.