London will continue to host the ATP Tour Finals until 2020 after agreeing a two-year extension contract.
The O2 Arena has staged the end-of-season tournament since 2009 and under the fresh terms the competition will also gain a new sponsor, the Nitto Denko Corporation.
"We're delighted to extend our stay in London," said Chris Kermode, ATP executive chairman and president.
"It's fantastic news to have such an ambitious and innovative company partner [Nitto] with our season-ending showcase in what is unquestionably one of the most exciting times in men's professional tennis in recent memory.
"We look forward to a successful partnership and to the continued growth of our season finale in London."
Andy Murray claimed the Tour Finals title in 2016 to finish the year top of the world rankings for the first time.
Rafael Nadal's sensational form on clay has put him top of the standings in the Race to London, with Roger Federer and Dominic Thiem completing the top three.
Five-time champion Novak Djokovic sits seventh, but Murray is in a lowly 13th place due to his troubles on clay.