Plans include the refurbishment of the Western Pier, with new departure gates and improved lounge facilities, re-development of the International Arrivals Hall and enhancements to baggage handling zones.
Construction work is scheduled to begin early next year.
London City Airport currently handles 70,000 flights per year and has permission to increase this to 120,000.
Airport CEO Declan Collier said: “With the investment we’ve announced today and further infrastructure work over the next three years, we can reach our permitted capacity, maintain our high standards and absorb some European air traffic from other airports in the South East that are beginning to feel the strain.”