It claims that this sends a clear signal to the UK government that Heathrow is a "ready-to-go, privately financed infrastructure project".
The globally renowned architectural practice, which was founded in the UK by Sir Nicholas Grimshaw, was selected after a rigorous assessment from a shortlist of four of the UK’s top architects which also included Zaha Hadid, HOK and Benoy.
This follows on from the announcement of Arup, CH2M, MACE and Turner & Townsend as Programme Client Partners in March.
They have been tasked with ensuring the programme is delivered to the highest industry standards in planning, innovation and quality.
Grimshaw were successful in the competitive tender process not only for their visionary concept designs, which pushed the boundary of what an airport could and should be, but also for their unique ideas around how Heathrow could be expanded in a sustainable but affordable way.
Grimshaw brings their experience of working on major transport projects across the world and were recognised as the stand out practice to help Heathrow deliver a world-class sustainable airport that will deliver innovation in passenger service whilst showcasing the best of British design.
Head of design at Heathrow, Barry Weekes, said: “We look forward to working with Grimshaw to develop their bold ideas so that once the government approves the Heathrow expansion, we can create a world-class sustainable hub airport which delivers for our passengers, our airlines and also helps to integrate Heathrow with our local communities.
"With the Concept Architect and Programme Client Partners now in place, we are now ready to begin the process of expansion once the Government makes the right choice for the whole of Britain.”
The airport insists that during a time of uncertainty following the result of the EU referendum, the government can send the strongest possible signal that Britain is open for business and confident in its future by expanding Heathrow.
The £16 billion privately funded infrastructure investment would be a much needed boost for the economy, creating jobs and growth across the UK.
Partner at Grimshaw, Jolyon Brewis, said: “We are passionate about designing a new future for Heathrow Airport; setting a benchmark for sustainable infrastructure, skilfully integrated with the communities it serves.
"Heathrow have ambitious plans for the expansion of the airport and we are proud to be selected to help deliver this inspirational vision.”