The ATP Tour Finals will be played behind closed doors in November.
The season-ending tournament, which features the best eight singles players and doubles teams of the year, will take place between November 15 and 22.
The event will be staged at the O2 Arena for the last time before moving to Turin in 2021.
The ATP Tour said it would follow government guidance and stage the event without fans but that it hopes some would be allowed to attend.
"ATP remains hopeful that later this year fans will be allowed to return into stadia in a socially distanced manner, following a series of pilot events being undertaken in the UK," a statement read.
Fans who have already bought tickets will receive full refunds and more will go on sale if government guidance changes and fans are able to attend.
The tournament has been staged at the O2 since 2009 but is moving to Italy from 2021-2025 and Novak Djokovic, Rafael Nadal and Dominic Thiem have already qualified for this year's event.
The ATP has also announced a revised calendar for the rest of the season following a five-month suspension due to coronavirus, which sees the Asian-swing scrapped.
The Tour resumes on 22 August with the Western & Southern Open in New York followed by the US Open at the same venue.
A shortened clay-court swing follows, culminating in the French Open on 27 September, before a five-week indoor European stint.
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