It is the second consecutive year it has received the accolade, and it has moved from 87th place in 2017 to 16th this year. Amadeus has also been included on the Dow Jones Sustainability Index for six straight years.
To determine the ranking, 5,994 companies with revenues higher than $1 billion were analysed on 17 quantitative key performance indicators related to governance, environmental, and social aspects.
Writing in his blog, Tomas Lopez Fernebrand, senior vice-president, general counsel and corporate secretary, Amadeus IT Group, said: "This prestigious achievement is linked to our purpose to shape the future of travel. We are committed to using our technology, expertise and global network to guarantee long-term travel industry sustainability.
"One of our core beliefs is that true long-term travel industry sustainability requires continuous checks that our operations and commercial endeavours are compatible and actually foster a more sustainable future.
"This exercise does not come naturally at first, and we need to constantly build this habit into all of our activities. Moreover, we believe all stakeholders in the travel industry need to be actively involved in understanding and nurturing these areas in order to meet today’s requirements without compromising the needs of tomorrow. Travellers will be expecting the companies they travel with to be doing just that."
French software company Dassault Systemes was ranked first, following a listing in 11th place last year. Its digital technologies have "assisted companies and governments alike in adopting renewables, experimenting with various forms of sustainable mobility and the creation of smarter cities", the report said.
Overall, companies from 22 different countries made the 2018 list, with the US, France and UK leading the pack. European companies dominated the rankings, accounting for 69% of listed companies, while North America and Asia accounted for 22% and 12% respectively.
However, only one UK company featured in the top 25: the publisher Pearson, which was ranked 15th.