Novstrup has served in the South Dakota Legislature since 2003. He was a member of the State House of Representatives from 2003-2009 and a member of the South Dakota Senate from 2009–2015. During a State Senate Affairs Committee hearing on Senate Bill 200, which called for the State of South Dakota to "suspend all direct or indirect resettlement of refugees and refuse to accept chain migration into South Dakota from citizens of countries appearing on any federal travel ban list", Novstrup argued that "we should be searching the people who look like the people who committed the crimes of 9/11." When asked in a local town hall the following week to clarify this quote, Novstrup remarked that "my quote was they should be looking at people that look like the hijackers of 9/11," he said. "I pointed out that a group of multi-racial people are the people we should be looking at." Novstrup further explained: "Here's what a terrorist looks like: they are of mixed racial background."
2002 When House District 3 incumbent Democratic Representative Burt Elliott was redistricted to District 2, Novstrup and incumbent Representative Larry Frost were unopposed for the June 4, 2002 Republican Primary; in the four-way November 5, 2002 General election Representative Frost took the first seat and Novstrup took the second seat with 5,685 votes ahead of Democratic nominees Tim Even and Anne-Marie Maldoon.
2004 Novstrup and Representative Frost were unopposed for the June 1, 2004 Republican Primary and won the four-way November 2, 2004 General election where Representative Frost took the first seat and Novstrup took the second seat with 5,824 votes ahead of Democratic nominees Teresa Flamboe and Thomas Black.
2006 When incumbent Representative Frost left the Legislature and left a District 3 seat open, Novstrup and his son David Novstrup were unopposed for the June 6, 2006 Republican Primary and won the November 7, 2006 General election, where Novstrup took the first seat with 5,010 votes and his son took the second seat ahead of returning 2004 Democratic challenger Thomas Black and Democratic nominee Ted Kneebone.
2010 Novstrup and former Senator Hoerth were both unopposed for both their June 8, 2010, primaries, setting up a rematch; Novstrup won the November 2, 2010 General election with 5,281 votes against Senator Hoerth.
