Scrabster Harbour Trust has appointed RJ Mcleod to redevelop and upgrade the Old Fish Market Pier, a job worth nearly £17 million.
The Scottish civil engineering contractor will provide new and improved deepwater berthing facilities, more storage areas and a new heavy lifting capability on the quayside.
It will also dredge out the channel to improve depths in the navigational approach to the harbour.
The harbour is used to import oil and the improved facilities are designed to help oil and gas exploration in the west of the Shetland islands and on the Atlantic frontier fields.
It will also help the local fishing industry and aid the development of the marine renewable energy industry in the Pentland Firth and North Atlantic.
The original OJEU notice priced the job at roughly £20m.
RJ McLeod saw off competition from two other bidders to secure the work with a £16.9m bid.
Gardiner and Theobald has been awarded a £252,700 contract to act as project manager for the job.