He then studied law with his father and his cousin Israel Washburn in Orono, Maine.
He was admitted to the Maine bar in 1847 and then moved to Oshkosh, Wisconsin Territory, where he continued to practice law.
From 1861 to 1864, Washburn served as probate judge of Winnebago County.
[2] Washburn resumed his career as a lawyer until 1879, when he resigned due to poor hearing.
Washburn died suddenly of heart failure at his home in Oshkosh, Wisconsin.