Associated British Ports is moving its Cardiff office to the newly-built Queen Alexandra House, near Cardiff Bay Barrage.
Cardiff is the focal point of all of ABP's operations in South Wales, which include the ports of Barry, Cardiff, Newport, Port Talbot and Swansea.
The move will happen in March, when the building will also become the headquarters for the Cardiff Harbour Authority. Work began on the site in January and was completed on target.
ABP's South Wales port director Budha Majumdar said: 'Our new port office complements the other landmark architecture for which Cardiff Bay has a growing reputation.
'It also provides the ideal solution in terms of providing modern, well-equipped office accommodation, which allows us to bring all of our operations under one roof.
'It is particularly fitting that we will be sharing the building with CHA, with whom we have a close working relationship, committed as we both are to the best interests of Cardiff's waterfront community.' On Monday, 50 ABP staff relocated to the 3,500m sq building, and this will allow ABP to consolidate its Welsh operations in one place. These include marine, estate management, engineering and the ABP division UK Dredging.