The Vikings confirmed Lynn's death Saturday with a statement on the team website. Lynn served as the team's general manager from 1975-90.
He is best remembered for one of the most lopsided trades in NFL history. The Vikings sent five players and seven draft picks to the Cowboys in 1989 for Walker, the running back Lynn considered the missing link to a Super Bowl run.
Walker never panned out in Minnesota, and Dallas used the riches of players and picks to lay the groundwork for three Super Bowl wins in the 1990s.
"The Vikings are deeply saddened by the passing of Mike Lynn," the team wrote in a statement on their website. "He was instrumental of the success of the Vikings for many years. Our thoughts and prayers go out to the Lynn family at this difficult time."
The Vikings did not cite a cause of death, but Lynn was reportedly in failing health for several years.
Known as a hard-nosed negotiator and one of the more colorful executives in Twin Cities sports history, Lynn rose through the Vikings' ranks under former owner Max Winter.
Lynn helped organize a front office that turned the Vikings into a consistent playoff contender that drafted and developed three Hall of Famers -- Randall McDaniel, Chris Doleman and John Randle, an undrafted rookie free agent. Lynn also played a big role in drafting several future Pro Bowlers, including Joey Browner and Keith Millard, and claiming Cris Carter, a troublemaker in Philadelphia who blossomed into one of the best receivers of his era in Minnesota, off waivers.
He also negotiated a deal with Winter that brought him 10 percent of the suite revenue from all Metrodome events over the life of the building, reaping a financial windfall for decades even after he left the team.
"RIP Mike Lynn," Twins president Dave St. Peter wrote on Twitter. "Few, if any, front office execs in Minn. sports history were more bold, colorful or controversial."
Lynn and the Vikings were always haunted by the decision to go all-in for Walker, a former Heisman Trophy winner and one of the greatest players in college football history who was acquired in the blockbuster midseason deal in 1989.
Walker rushed for 1,514 yards and five touchdowns in 1988, his third season with the Cowboys after coming to the NFL from the USFL. Lynn and the Vikings felt all that was preventing them from making a run at the Super Bowl was a stud running back, so they went after Walker.
The Vikings received Walker and four draft picks for linebackers Jesse Solomon and David Howard, running back Darrin Nelson, cornerback Issiac Holt, defensive end David Howard and a staggering seven draft picks, including three first-rounders and two second-rounders.
Cowboys coach Jimmy Johnson used the incredible bounty to wheel and deal through three drafts, landing stars Emmitt Smith, Darren Woodson and Russell Maryland to help construct the framework of the team that dominated the early 1990s.
Walker had a dazzling debut, rushing for 148 yards against Green Bay. But that was by far the highlight of his time in Minnesota. He lasted just two more seasons with the Vikings before moving on to Philadelphia.