A planning application is due to be submitted next month following public consultation and outline designs being drawn up.
The scheme covers 4.5km of coastline from the Long Curtain Moat in the west to the Eastney Battery in the east.
The seafront, along with Southsea Common, is a focal point for recreation and tourism and is hugely important for the city. But at present the principal design has highlighted a funding gap of around £20m from the £95m initially budgeted.
Balfour Beatty has worked on the project in the early planning stages under a £1m pre-construction agreement, heading design work with Arup.
Funding for construction will now depend on the full business case being submitted and approved by the Environment Agency and Treasury.
Present plans will split the works into half a dozen phases to be delivered over eight years.
The city council is now inviting firms to prequalify with the hope of signing up a contractor in early September with the target of starting works by Spring 2020, subject to funding approval.
Ahead of shortlisting a bidders day will be held on 1 May with a presentation at the Portsmouth City Council Civic Offices followed by a guided site visit of the frontage
After this procurement chiefs plan to shortlist three firms to bid a two-stage open book early contractor involvement.
Click here to express an interest.