Born in Marion County, Willey became a lawyer and a powerful public speaker known for quoting classic literature and the Bible.

Though he first opposed splitting from Virginia, he later supported West Virginia statehood and helped pass the bill in Congress. He also negotiated the Willey Amendment, which required the gradual emancipation of enslaved people in West Virginia, saving the statehood bill in Congress when it appeared to be on the brink of failure. Willey served as one of West Virginia's first two U.S. senators and supported voting rights for African Americans. He stayed active in public life until his death in Morgantown.