The works include redeveloping the security processing area to provide more boarding card gates, a dedicated security preparation area and a refreshed waiting area with new flooring and lighting.
Commenting on the investment, David Winstanley, COO for Birmingham Airport, said: “This investment follows record passenger growth and to ensure that we’re prepared for the coming summer period, when the airport will welcome new long-haul services to New York, Boston and Toronto, as well as many new popular short-haul destinations.
“The service we give our customers is an absolute priority for us so we’re investing a great deal to improve the airport journey.”
The airport is also developing its retail and catering offer, with the recent opening of The Factory restaurant and the arrival of Kurt Geiger to its airside shopping experience.
Later this spring, a new Bottega prosecco bar will open as well as wrapchic – an Indian inspired burrito and sandwich outlet.
A covered walkway to the terminal is also under construction for those who choose to walk to the terminal from the free drop off car park, and a new 178-guestroom Hilton Garden Inn hotel will open in the summer.
New digital wayfinding and signage will be introduced before the summer season.
Additional staff are being recruited in key customer facing areas, including terminal operations, customer relations and security officers.
Birmingham Airport recorded the busiest year in its 78 year history in 2017 when almost 13 million passengers passed through its terminal.
In total, 12.9 million passengers travelled through the airport over the course of the calendar year, over 1.3 million more people than in 2016 giving a healthy increase of 11.5% year on year.
The busiest month fell in August when almost 1.5 million passengers were recorded in a single month, giving a significant 16.2% increase when compared to the same month the year before.
Over the course of the year, there were seven months in which over a million passengers were recorded and over thirty months of consecutive record breaking growth.
David Winstanley, the airport's chief operating Officer, said: “Last year we celebrated the busiest 12 months in our history.
“During 2017, we saw the launch of Jet2.com and Jet2holidays and the return of British Airways and bmi regional. Emirates maintained a strong presence in the region and introduced its second daily A380 aircraft onto its established lunchtime service between Birmingham and Dubai.
“The year was indeed one of celebration but also commiseration as we sadly saw the demise of a long-established airline, Monarch.
"This airline carried an average of 5,000 passengers per day from Birmingham but we have seen some existing carriers and new carriers pick up almost all of this capacityalready to reduce the impact on our passengers.”