Spurgeon was set to hit unrestricted free agency after the 2019-20 season. The 29-year-old set career highs in goals (14), assists (29), and points (43) last year.
The new deal will make him the 11th-highest-paid defenseman in the league in 2020-21, just ahead of teammate Ryan Suter.
The 5-foot-9, 167-pound Spurgeon may not have the conventional look of an elite shutdown defender, but that's exactly what he is. Among blue-liners who logged at least 500 minutes at five-on-five last year, Spurgeon allowed the 15th-fewest expected goals and the 11th-fewest high-danger scoring chances per 60 minutes, according to Natural Stat Trick. And they aren't soft minutes - Spurgeon matches up against opponents' top lines.
The extension marks new general manager Bill Guerin's first major splash with the Wild.