Henry Horner attended the University of Chicago and graduated from IIT Chicago-Kent College of Law in 1898. He practiced law and served as a probate judge from 1915 to 1931. Horner transitioned from the legal profession to a political career, culminating in his election as governor during the Great Depression. He implemented fiscal measures, including Illinois's first permanent sales tax, and took a firm stance against corruption and patronage.

Henry Horner's political philosophy reveals a calculated approach to fiscal responsibility and anti-corruption, marked by an unusual willingness to implement and increase sales taxes during the Great Depression. His legislative actions, including Illinois's first permanent sales tax, demonstrate an ideologically agile stance that prioritizes stabilizing state finances over ideological purity. Horner's opposition to Chicago's Democratic political organization highlights a confrontational yet strategic effort to combat graft, suggesting a nuanced understanding of political power dynamics. His support for Democratic candidates, like Scott W. Lucas, further underscores a pragmatic yet principled approach to party loyalty.