The scheme, for developer Charles Church, includes plan for shops, 11 townhouses and 27 flats and will form part of the ongoing regeneration of the town's docks.
Both the two four-storey apartment blocks and the houses will have views over the water, while the western side will face on to Waterside Square, a new 'urban' space with ground-level retail facilities. Car parking will be hidden from public view in a landscaped court to the rear of the development.
Practice director Bruce Calton said: 'It is a privilege to work on a masterplan alongside clients who share the vision in seeing quality, contemporary architecture developed as part of the new urban theme.
'It has been a challenging and rewarding project creating a vibrant mixed-use scheme that will spearhead quality architecture and create a true sense of place in such a spectacular waterside environment. Portishead Quays is set to become one of the leading waterside regeneration projects,' he added.
Work is due to start on site towards the end of the year.