Mason began his political career in 2010, when at the age of 25 he was elected to the Maine Senate after defeating 18-year incumbent
John Nutting. He went on to represent District 17 until 2014 and District 22 from 2014 to 2018. Mason was re-elected in 2012 by 28 votes over Democrat Colleen Quint of Minot. During his first term, Mason sponsored legislation to allow
charter schools in Maine, which was signed into law by Governor Paul LePage in June 2011. After Republicans took control of the Maine Senate in 2014, Mason was elected by his colleagues as Senate Majority Leader, a position he held until he was term-limited in 2018. That year, he ran for
Governor of Maine, finishing second to
Shawn Moody in the Republican primary. In January 2021, Mason was appointed to the Androscoggin County Commission to fill the vacancy left by Isaiah Lary. He was elected to a full four-year term in 2024, with that term set to expire on December 31, 2028. ==Electoral history==