Mackley Construction Ltd has been chosen to deliver the next phase of coastal defences as part of the North Portsea scheme, which will safeguard more than 4,000 homes and almost 500 businesses.
The defences come as the fourth of five phases in the £58m project and will be split into two sections.
The first will begin at the top of Eastern Road near Kendall's Wharf, covering an area of 300 metres. Work will start at the end of September and will involve raising the road and constructing an earth embankment.
Councillor Dave Ashmore, Portsmouth City Council's environment boss, said: 'The continuation of this work, coupled with the other coastal defence projects taking place are future proofing Portsmouth for coming generations.
'This investment and subsequent improvement in public realm and facilities will ensure Portsmouth is a great place to visit, live and work.'
The second section of work involves the construction of a sea wall along 2.1km of coastline down Eastern Road. If planning approval is granted, Mackley will begin work in this area in September 2020.