Nelson, all All-American at nearby Florida and the 21st overall pick in the April draft, signed a five-year deal worth $13.2 million. The contract includes $7.1 million guaranteed.
Nelson had been the last remaining unsigned player, but the deal got done just in time for Nelson to make coach Jack Del Rio's welcome meeting Friday evening.
The Jags signed Durant earlier in the day. He got a four-year deal that includes $1.72 million guaranteed. He is scheduled to make $285,000 this season, followed by $370,000 in 2008, $460,000 in 2009 and $550,000 in 2010.
Durant, a 6-foot-1, 232-pounder from Hampton, was the sixth linebacker drafted this year and the first from a Division II school. He was the Mid-Eastern Athletic Conference defensive player of the year three times.
He finished his college career with 353 tackles, 47 tackles for a loss, 10 sacks and four interceptions.
The Jaguars believe he can be equally productive at the next level. They like his speed and aggressiveness, and expect him to provide an immediate impact on special teams and maybe work his way into the starting lineup alongside Mike Peterson and Daryl Smith.
Nelson already has earned a starting spot. He takes over at free safety in place of Deon Grant, and he won't have veteran Donovin Darius to help out.
The Jaguars released Darius last month, leaving third-year player Gerald Sensabaugh to fill his shoes.
Although defensive tackle Marcus Stroud (ankle) has received medical clearance to practice, several players will be sidelined for the start of camp.
Defensive end Reggie Hayward (Achilles' tendon) has not been cleared to practice. Tight end George Wrighster (labrum) and rookie defensive end Brian Smith (hip) are expected to miss at least part of camp, and third-string quarterback Quinn Gray could be headed to the physically-unable-to-perform list because of a sprained ankle.
Even with Gray out of the picture, the Jaguars don't expect to add free agent quarterback Daunte Culpepper to the roster.
Del Rio told his quarterbacks, including starter Byron Leftwich, in June that the team would pursue Culpepper if he became a free agent. But Del Rio said on his radio show this week that it was doubtful the team would sign Culpepper, who visited Tampa Bay after getting his release from Miami.
"I doubt it's going to happen," Del Rio said. "It just doesn't seem like a good fit for whatever reason."
Also, offensive tackle Maurice Williams agreed to restructure his contract. Williams was due to make $3.5 million this season, but will now make $2 million. In return, the Jags voided the final two years of his deal.
Williams lost his starting job when the team signed free agent Tony Pashos. The Jags tried to trade Williams during the draft, but didn't get an offer they liked and decided to keep the longtime starting right tackle.
Now, Williams likely will be a backup this season and then hit the free agent market next year.