According to multiple reports, the deal is worth $81 million, including around $40 million guaranteed. The fourth-year wideout was scheduled to make $1.9 million in 2018, the final year of his rookie contract.
"To Vikings fans and everybody, you guys are stuck with me for a little longer," Diggs said with a smile in a video posted on the team's Twitter account. "I just signed my extension, I'm happy to be a part of this organization."
A fifth-round selection from Maryland in the 2015 NFL Draft, Diggs gained 849 yards on 64 receptions last season. He also scored eight touchdowns. He became the first player in NFL history to record at least 13 receptions in consecutive games with 13 against Detroit and 13 at Washington last November.
--Free agent wide receiver Eric Decker worked out with the New England Patriots, who are looking to bolster their depth at the position.
Injuries to Jordan Matthews (hamstring), Malcolm Mitchell (knee) and Kenny Britt (hamstring) and a pending four-game suspension for Julian Edelman are prompting New England to weigh external receiver options.
Decker, 31, played all 16 games and made eight starts for the Tennessee Titans last year. He caught 54 passes for 563 yards and one touchdown.
NFL Network's Ian Rapoport reported the deal "is not something that, at present, is currently being worked on," despite the pass-rusher's holdout from training camp.
The team has consistently said it plans to re-sign Mack to a long-term deal as he enters the final year of his contract, but there have been no indications of progress. Mack skipped all of the Raiders' offseason workouts before failing to report to training camp last week.
--Roquan Smith remains the only unsigned 2018 NFL Draft selection, and Chicago Bears general manager Ryan Pace said the sides are "working through" the items holding the contract up.
Pace declined to elaborate on the details of Smith's holdout. The linebacker, who was selected with the No. 8 overall pick from Georgia, has missed nine training camp practices. The Bears play in the Hall of Fame Game on Thursday, which allowed the team to begin camp early.
Smith was expected to compete for a starting linebacker role this season and to bolster the Bears' defense. Pace said despite time away from practice, Smith still could start.
--Seattle Seahawks wide receiver Doug Baldwin and defensive end Dion Jordan are expected to miss much of training camp as the team takes a cautious approach with their injuries, head coach Pete Carroll said.
Baldwin missed his third straight practice with a sore knee, which Carroll told reporters the wideout was dealing with "coming into camp."
Carroll also told reporters that Jordan -- who has yet to be activated from the physically unable to perform list -- is going to be out for some time with "a stress issue." Jordan had a knee scope earlier this offseason, but Carroll said the new issue is unrelated to that knee and is on the other leg.
--First-round pick Vita Vea will miss some time with a left calf injury, but the Tampa Bay Buccaneers were relieved that the defensive tackle didn't sustain a more serious injury, head coach Dirk Koetter said.
Koetter added Vea will be out for "a little bit" but declined to give a more specific timeline. The 6-foot-4, 347-pound tackle attended Monday's practice while using a scooter with his foot in a walking boot, and he stood with some weight on the leg toward the end of the session.
Vea, 23, was carted off the field on Sunday after getting hurt during the team's first padded practice of camp. The 12th overall pick from April's draft has drawn praise from Koetter and defensive coordinator Mike Smith.
--Field Level Media