The agency will initially determine the quality and quantity of data, then work on analysis of the airline's customer base in order to maximise marketing effectiveness.
Sarah Dixon, brand manager at bmibaby, said: "Through our website, call centres and other sales outlets, we have a very rich supply of customer data, we want to be able to use this information to take an in-depth analysis and develop solutions to serve our loyal customers and potential new flyers."
EHS Brann will use segmentation and analysis to break down customers by characteristics, behaviour and repeat booking patterns.
Richard Greenhalgh, managing director of EHS Brann Discovery, said: "In the crowded online travel market, providing outstanding customer service is a must to stand out among competitors.
"By creating a single customer view from various customer data sources, we will be able to help bmibaby have a clearer understanding of its customers, be able to anticipate their needs, and communicate with them on a personal level."