The players were punished by the league in May when the NFL identified them as having leadership roles in a program where players were given cash rewards for knocking opponents out of games from 2009-2011.
In its four-page ruling, the three-member panel said that under the collective bargaining agreement between the NFL and NFL Players Association, league commissioner Roger Goodell did not have the authority to suspend players for accepting money from a pool for big plays.
But the panel said Goodell has the right to suspend players who attempt to injure opposing athletes.
While the players have been reinstated in time for the NFL's season-opening weekend of game, Goodell can apply new bans if he proves there was an intent by the players to injure.
"Consistent with the panel's decision, Commissioner Goodell will, as directed, make an expedited determination of the discipline imposed for violating the league's pay-for-performance/bounty rule," NFL spokesman Greg Aiello said.
"Until that determination is made, the four players are reinstated and eligible to play starting this weekend."
Saints linebacker Jonathan Vilma was initially suspended for the entire 2012 NFL regular season, free agent Anthony Hargrove for eight games, Saints defensive end Will Smith for four games and Cleveland Browns linebacker Scott Fujita three games.
"Victory is mine!!!!" Vilma said on his Twitter account.
The ruling does not lift the bans given to coaches Gregg Williams, Sean Payton and Joe Vitt.
Williams, the Saints' former defensive coordinator, was suspended indefinitely by Goodell, head coach Payton for the current season and assistant Vitt for six games.
- NFL Players Association