The investment also includes an upgrade of the airport’s central security area and hold baggage screening facilities, as well as the purchase of a new fleet of Airport Fire appliances.
According to the Irish gateway, "the capital expenditure will further enrich and enhance the overall passenger journey through the airport", with the upgrade of the central security search area aimed at more efficient processing for all departing passengers.
There will be in excess of a 30% increase in retail space, with an expanded offering from World Duty Free and WH Smith.
F&B facilities will be expanded by 25%, with broader choice for customers being introduced along with partner HMS Host, which operates existing facilities including the Bushmills Bar.
Additionally, customer seating will be more than doubled, as will airside customer washroom facilities, which will also be fully refurbished.
The completed works will be contained within the current terminal building and will be completed by October 2018.
Belfast City Airport announced the infrastructure investment at a breakfast briefing for key stakeholders on Tuesday morning at the Europa Hotel in Belfast.
Brian Ambrose, chief executive of Belfast City Airport, said: “In keeping with our overall mission of delivering an airport experience that exceeds our customers’ expectations, Belfast City Airport is fully committed to continually improving the overall journey for our passengers.
"The £15m investment in our infrastructure is another major reinforcement of our commitment.
“The upgrading of our departure lounge and retail offering will provide greater choice and significantly enhance the experience for our core business and leisure passengers as they travel through the airport.
“The strategic designs help future-proof the airport and we look forward to continuing what has been a successful period across many areas of our business.”
Speaking during the unveiling of the plans, Ambrose said the investment reinforced the contribution the airport is making to key Belfast City Council growth strategies.
He added: “As a rapidly-evolving city and, as one of Belfast City Council’s key stakeholders, we are proud to play our part in supporting Belfast’s growth and in driving forward strategies to further enhance the city’s reputation on a global stage."
The new terminal reconfiguration was designed by Todd Architects and the main elements of the refit will be carried out by H&J Martin on behalf of the airport.