A Republican, he served two terms in the Washington House of Representatives for the 5th district, comprising much of the eastern third of King County.

Magendanz was endorsed by The Seattle Times in 2012, 2014, 2018, 2022, and 2024 and consistently received an Outstanding rating from the Municipal League of King County.

[2] After graduating, Magendanz served in the United States Navy until 1997 as a nuclear submarine officer and was honorably discharged as a lieutenant.

Magendanz entered into a career of software development working for Microsoft, where he shipped 16 products and earned over 20 patent awards.

[9] Magendanz has sponsored and passed legislation alleviating teacher shortages, improving vision screening in schools, addressing truancy reform and providing consumer protection for retirement communities.

[11] Magendanz also sponsored legislation establishing distance and near-vision testing for students in all Washington State school districts.

[12] The Cybersecurity Jobs Act[13] was designed to help the private sector develop assets to protect industries and infrastructure from cyber attack.

The legislation created a 24-credit high school diploma to boost science, technology, engineering and math instruction.

[citation needed] That same session, Magendanz sponsored legislation that gave electric cars Washington state sales tax exemptions.

The goal of these committees has been to increase funding for public schools in light of a Washington State Supreme Court ruling.