The suspensions of those players, plus unsigned free agent Anthony Hargrove, for their roles in New Orleans' pay-for-pain bounty scandal were lifted Friday by a three-member appeals panel.
The league reinstated them all a few minutes later.
Vilma plans to attend Sunday's season opener against the Washington Redskins, a team source previously told ESPN's Ed Werder. But the three-time Pro Bowler, who is recovering from a knee injury, cannot play since the Saints used their roster exemption and did not include him on their active roster.
Smith did not practice this week and his status has not officially been determined, but the defensive end likely will play in the NFL debut of Washington rookie quarterback Robert Griffin III, the source told Werder.
Fujita, now with the Cleveland Browns, also may play Sunday against Philadelphia.
And Hargrove can start talking to NFL teams about giving him another shot after he was cut by the Green Bay Packers during the preseason.
The ruling does not affect New Orleans coach Sean Payton (suspended for the season), interim coach Joe Vitt (six games) or general manager Mickey Loomis (eight games).
There's no telling how long the reprieve for the players will last.
Coming just two days before the first full slate of NFL games this season, the ruling is a setback for commissioner Roger Goodell and the league. But while the decision allows the players to rejoin their teams, it does not permanently void their suspensions.
NFL spokesman Greg Aiello said Goodell would "make an expedited determination of the discipline imposed" for violating the league's bounty rule.
"Until that determination is made, the four players are reinstated and eligible to play starting this weekend," Aiello said.
League sources told ESPN NFL Insider Adam Schefter that Goodell is likely to reach a new decision in the coming weeks, but it will not be before this weekend's games.
Vilma, who had been suspended the whole season, tweeted: "Victory is mine!!!! -stewie griffin."
Added Fujita: "I'm overwhelmed with all the support. Thank you so much everyone. Can't tell you how much it means to me."
If Vilma (base salary of $1.6 million), Smith ($825,000) and Fujita ($3.65 million) are on their respective teams' rosters Sunday, their base salaries will be guaranteed for the 2012 season.
"I think it is an extremely strong statement that a three-judge panel unanimously ruled to lift the suspensions," Saints quarterback Drew Brees told Werder. "It makes you feel like they took a very hard look at all the evidence there and saw that we were in the right. ... Today makes you feel like justice has been served."
While the panel did not address the merits of the NFL's bounty investigation, it found that Goodell overstepped his authority in hearing the players' appeals of their punishments for participating in the Saints bounty program, which paid cash bonuses for hits that injured opponents.
The panel's decision states that Special Master Stephen Burbank, not Goodell, should discipline players for receiving money from a pool that paid for big plays. Goodell's role, the panel said, should be limited to whether he can prove the players intended to injure opponents, which would fall in the category of conduct detrimental to the game. Players and coaches implicated in the bounty pool have testified under oath in a related federal court case they never intended to injure opposing players.
"Whether the commissioner tries to readdress the situation or not is his call," said Peter Ginsberg, Vilma's attorney. "We are certainly hoping the appeals board has made it clear the commissioner tried to grab jurisdiction and impose penalties over an area he does not have oversight. ... The factual record in the court makes it clear he has acted in a biased and inappropriate manner."
In a memo sent to all 32 NFL teams after the ruling and obtained by The Associated Press, NFL legal counsel Jeff Pash emphasized that "nothing in today's decision contradicts any of the facts found in the investigation into this matter, or absolves any player of responsibility for conduct detrimental. Nor does the decision in any way suggest what discipline would be appropriate for conduct that lies within the authority of the Commissioner."
The league's investigation found that Saints coaches and players, led by former defensive coordinator Gregg Williams, ran a program from 2009-11 that offered cash payouts for hits that injured opponents. It said specific bounties were placed on quarterbacks Kurt Warner and Brett Favre in the 2009-10 playoffs.
The Saints open their season at home against Washington on Sunday, while the Browns host Philadelphia.
The NFL granted roster exemptions to the Saints for both of their suspended players and to the Browns for Fujita, meaning New Orleans could carry up to 55 players and Cleveland 54.
Earlier this week, Saints interim head coach Aaron Kromer said Smith, who participated in training camp and the preseason before he began serving his four-game suspension on Monday, would be ready to play against Washington if available.
Vilma's status was not as clear. His season-long suspension began before training camp and he has been trying to work his way back from offseason surgery on his left knee.
Saints players had just finished practice when they received word of the panel's ruling.
"It's huge," said Saints safety Malcolm Jenkins, a defensive captain. "Those are two huge leaders we've got. They're great players. We've got a talented team, but you add Will Smith and Jonathan Vilma, our talent level goes up that much. For our team, it's a break."
Even if Vilma could not play right away, Jenkins said his presence in the locker room and meetings would be valuable.
At Browns headquarters, linebacker D'Qwell Jackson was sure the 33-year-old Fujita would be able to come back and have an immediate impact.
"I'm confident Scott has been keeping his conditioning up and he knows the system," Jackson said.
"He's got what, 12 years in? He'll be fine. If he's able to come back there will be a lot of excitement in this locker room."
Fujita was barred from Cleveland's training facility this week, but he stayed in town and worked out on his own at nearby Baldwin Wallace University in the event the suspension was lifted. Fujita, who serves on the NFLPA's executive committee, had expressed confidence he would be on the field in Week 1.
Hargrove, docked eight games, was released last month by Green Bay and is not currently with a team.
The appeals panel consisted of retired federal Judge Fern Smith of San Francisco, retired federal Judge Richard Howell of New York, and Georgetown professor James Oldham. It met in New York last week to hear arguments from the NFL Players Association, which appealed Burbank's ruling that Goodell had the authority to hear and rule on the players' appeals of their suspensions. NFL attorneys had asked the panel to affirm Burbank's ruling, but the panel sided in large part with the union.
The decision likely means that consolidated federal lawsuits brought against the NFL by Vilma and the NFLPA on behalf of the other three players are likely on hold until Goodell reissues punishment. It also spared U.S. District Judge Ginger Berrigan from having to decide before Sunday on a temporary restraining order requested by the players.
Information from ESPN NFL Insider Adam Schefter, ESPN's Ed Werder and The Associated Press was used in this report.