Work will start on site next week and be completed by summer 2012, in time for the Olympics.
The hotel is the latest stage in ambitious expansion plans for the Essex airport which recently confirmed it would become a hub for easyJet
The 129-bedroom hotel has been designed by Leach Rhodes Walker and the five-storey building will feature a restaurant and private dining room on the top floor.
London Southend Airport is operated by transport giant the Stobart Group and the airport’s managing director, Alastair Welch, said: “High quality and convenient hotel facilities are essential ingredients of successful regional airports and an important part of our plans to modernise London Southend airport.
“This hotel will greatly improve facilities for passengers, as well pilots and flight crew using the airport, whilst also becoming an exciting new venue and resource for local businesses and people.
The contract is the latest hotel job for Willmott Dixon after delivering ten across the country already this year.
Hotel sector manager Tim Wheeldon said: “This hotel is a considerable investment and reinforces Stobart Group’s plans to develop the airport into a striking and modern new facility.
“We are working to a tight programme with completion scheduled before the Olympics, and we will be utilising local labour and suppliers as and when we can during the build and fit out process.
“We are experienced hotel contractors and this, along with a healthy pipeline of additional work, underlines our ongoing commitment to the hotel industry.”
The operator of the hotel will be announced in due course.