At the 2015 Winter Universiade, Walstad skipped the University of Oslo rink to a gold medal, defeating Russia's Evgeny Arkhipov in the final.

To start the 2017–18 curling season, Walstad played in his first Grand Slam event, the 2017 GSOC Tour Challenge.

Later in the year, Waldstad skipped Norway at the 2018 World Men's Curling Championship, leading the team to a 7–6 finish in 5th place.

In November, the team played in the 2018 European Curling Championships, where Waldstad led Norway to a 5–4 record in fifth place.

Later in the season, Walstad was named as the alternate on the Norwegian team, skipped by Magnus Ramsfjell at the 2019 World Men's Curling Championship.

He found more success at the 2014 European Mixed Curling Championship, where he would lead his rink of Kristin Moen Skaslien, Magnus Nedregotten and Julie Kjær Molnar to a silver medal finish, after losing to Sweden in the final.