The 34-year-old running back played in only three games last season before a torn ACL and broken hand suffered in a game against the New York Giants ended his season prematurely.
Eagles coach Doug Pederson lobbied to keep Sproles for another season.
"I'm excited to get him back and I know he is too," Pederson said. "Just looking forward to getting him back in the building and seeing that smiling face here."
Some of the trades the Eagles made in the NFL Draft this weekend freed up cap space to sign Sproles.
"It's been a priority to get Darren back," Eagles vice president of football operations Howie Roseman said. "I think I got the message when coach would come by my office, maybe once a day, twice a day and say, 'when are we getting Darren? When are we getting Sproles back?'
"I said, 'I got the message, coach.' But we all wanted Darren back. We talked after the Super Bowl with Darren that it would be a priority for him to come back. He's a freak. The things he's doing in his rehab, it's amazing."
The Eagles expect Sproles to be healthy and ready for the season opener in September.
Sproles' value is mostly as a dual weapon out of the backfield. He has averaged 4.6 yards per carry and caught 154 passes in four years in Philadelphia.
In 171 NFL games, Sproles has rushed for 3,366 yards (4.9-yard average) with 22 touchdowns and caught 532 passes for 4,656 yards and 30 touchdowns with the Chargers, New Orleans Saints and Eagles.
"When we sign Darren, everyone in the building is excited," Roseman said. "The owner is excited, the head coach is excited, the offensive coordinator is excited, the special teams coordinator is excited, the vice president of player personnel is excited."
The Eagles did not select a running back in this year's draft.