Australian Open and French Open winner Djokovic, Wimbledon champion Andy Murray and Wawrinka are the first three players all confirmed for the season-ender at the O2 Arena.
Wawrinka, 31, claimed his third grand slam title by defeating Djokovic in four sets, adding to the 2014 Australian crown and 2015 French Open.
It will be his fourth appearance at the Tour Finals where he will be looking to better his three semi-final runs.
"At the beginning of the season, it is always my goal to be in the top eight and qualify for London," said Wawrinka.
"It is great to be able to secure a spot once again this year after a fantastic two weeks in New York. I look forward to returning to The O2. I love playing there."
Wawrinka has won four titles this year having also won in Chennai, Dubai and Geneva.
(Reporting by Martyn Herman; editing by Amlan Chakraborty)
