Now VSBW, a joint venture between VolkerStevin and Boskalis Westminster, can start work later this year on 4.5km of coastline from the Long Curtain Moat in the west to the Eastney Battery in the east.
Present plans will split the works into half a dozen phases to be delivered over eight years.
Funding was the final hurdle the Portsmouth City Council project had to overcome.
The project team has worked closely with the Environment Agency to secure approval, despite unprecedented demands placed upon central government finances at this time.
Once finished, the scheme will protect over 10,000 residential and 700 non-residential properties in Southsea from coastal flooding.
Cllr Hugh Mason, Cabinet Member for Planning Policy & City Development, said: “This is excellent news and it is the culmination of many years of planning and careful negotiation.
“The scheme has been challenging because we had to plan not just to build sea defences but to plan them in a way which would protect and enhance the unique character of the Southsea seafront, so loved by both local people and visitors.”
The first phase of work to start will be between Long Curtain Moat and Clarence Pier, while detailed designs for other sections are being developed.