Rosendale spent his career working in real estate and land management. He grew his family real estate business into a full-service firm with 65 agents and four offices. He served twice as chairman of the Glendive Agri-Trade Expo committee. Rosendale first ran for the Montana State House in 2010 after being urged by his friends and neighbors. He served one term in the State House before being elected to the State Senate in 2012.