Members of both organisations will benefit from insights into the business travel and rail sectors, with data on domestic and international rail travel generated from the Trainline’s 96 million monthly users.
Clive Wratten, chief executive of the BTA, said the rail sector is a "crucial part of the business travel eco-system".
"Having Trainline onboard will be a great benefit to our members as we steam ahead on our plans for the rail sector," he added.
Meanwhile, president of Trainline partner solutions Champa Magesh said the new partnership will help the travel sector "deliver the experience that business travellers are looking for".