The sunny heart will replace the current globe symbol, changing on Thomas Cook's airline fleet, stores and website.
For the first time in the company's 172 year history, just the one logo will be used which, it said, is key to simplifying the brand - in turn, vital for growth.
Harriet Green, Group Chief Executive of Thomas Cook, said:
This major milestone in the transformation of our company, as we continue to develop our product offering and focus on our omni-channel approach, is much more than the rollout of a new logo. It symbolises how we are leveraging the combined power of the group to maximise our presence in the mind of customers, whilst helping to reduce cost.
Thomas Cook's leading brands, such as Elegant Resorts in the UK and Condor in Germany, will be attached to the sunny heart brand in various ways, the company says.