It is the 11th successive year Federer has qualified for the season-ending showpiece, a tournament which will again take place at the O2 Arena this season.
The 30-year-old secured his spot in the elite eight-man field by winning for a seventh time at Wimbledon. He will also be seeking a seventh Tour Finals trophy in November having won the tournament for a sixth time in 2011.
Novak Djokovic and Rafael Nadal have also qualified for the event. They are guaranteed to finish the year in the world's top eight following results at Wimbledon.
Australian Open winner Djokovic, champion in 2008, qualifies for the sixth year in a row after his run to the semi-finals in SW19.
And despite his shock second-round loss to Lukas Rosol at Wimbledon, French Open champion Nadal will also be in attendance at the O2. It is the eighth straight year he has qualified.
Tournament director Andre Silva said: "We look forward to welcoming Roger, Novak and Rafa back to The O2 in London this November, where fans will have the chance to see them battle once again for the coveted last title of the ATP World Tour season, where so much will be at stake for all of them."
Five places remain to be filled, with Wimbledon runner-up Andy Murray leading the charge.
The tournament takes place from November 5-12, with the final this year taking place on a Monday.