The news followed the resignations of Robin Haase, Jamie Murray and Sergiy Stakhovsky before Wimbledon following a seven-hour meeting to thrash out a range of issues including a replacement for former player representative Justin Gimelstob, Reuters reported.
"They will begin their roles with immediate effect and will serve until the end of the existing term which runs through to Wimbledon 2020," a statement from the ATP read.
The coaching representative slot vacated by Daniel Vallverdu in July remains unfilled.
Friction has dogged the ATP Player Council, whose president is world number one Novak Djokovic, this year since ATP president Chris Kermode failed to gain support for another term.
Other issues include the distribution of prize money.
Gimelstob was one of those who sided against Kermode but resigned in May after coming under pressure to do so after pleading no contest to an assault charge.
The American former Tour player has continued to try to clear his name.
Swiss Federer, 20-time Grand Slam champion, is a former president of the Player Council while Spaniard Nadal, who has won 18 majors, quit his vice president role in 2012.
The player council, which represents the players in the ATP's joint governance structure, consists of 12 members, including six members of the world top 100 in men's singles.
South African Kevin Anderson is vice president and Americans John Isner and Sam Querrey are also on the Council.