Republican Justin Eichorn defeated DFL incumbent Tom Saxhaug by a slim margin.
Eichorn had 50.58 percent or 20,245 votes to Saxhaug's 49.22 percent or 19,700 votes.
Saxhaug, 68, Grand Rapids, served District 3 in the Minnesota Senate from 2003 to 2012 and has represented District 5 since 2013. He serves on the finance committee.
The retired insurance agent represents Beltrami, Cass, Hubbard and Itasca counties.
Saxhaug, a former county commissioner, has been a key player in St. Paul on education and natural-resource issues, the Duluth News Tribune reported. He serves as chairman of the Finance Committee's State Departments and Veterans Budget Division and also serves on the K-12 Education Finance Division.
At a candidate's forum earlier this month, Saxhaug said he's proud of his legislative record in job creation efforts and education, especially expanding job training efforts across the Iron Range.
Eichorn's family owns and operates Glen's Army Navy gun and sporting goods store in Grand Rapids. He is a lifelong resident of the area. The Duluth News Tribune reported he said economic development efforts have been sluggish and the area lacks opportunities for young people.
Eichorn, 32, ran against DFL state Rep. Tom Anzelc in 2014 and came up short, before his successful run against Saxhaug. Eichorn defeated a Republican primary rival in the Senate race in August with 73.26 percent of the vote to 26.74 percent for Lavern "Pedie" Pederson of Bemidji. Eichorn served on the Grand Rapids Housing and Redevelopment Authority.