Cranley was born in Green Township to John Joseph "Jay" Cranley and his wife, Susan. His father is a life estate planner and Vietnam veteran who served in the United States Army, and his mother a former teacher and librarian. Cranley was raised in the Price Hill neighborhood of Cincinnati. He attended St. William's Primary School and graduated from St. Xavier High School in 1992. He graduated from John Carroll Universitymagna cum laude in Philosophy and Political Science and served twice as student body president. He earned his JD from Harvard Law School and a Master of Theological Studies from the Harvard Divinity School. He taught two undergraduate legal and philosophy courses at Harvard College while attending graduate school. During his second and third years at Harvard Law School, he worked as a student attorney for people who could not afford legal counsel. In his third year of law school, he was elected First Class Marshal and delivered the Harvard Law School graduation speech on behalf of his class. In 2019, Cranley was voted reader pick for "Best Conservative" in Cincinnati CityBeat's annual Best of Cincinnati.
Cincinnati City Council
Cranley served on city council from 2000–09. In 2003, he led the push to create Tax Increment Finance districts in Cincinnati. Cranley served on the following committees: Arts, Culture, Tourism & Marketing; Economic Development; Law and Public Safety; and the Transportation & Infrastructure sub-committee. Cranley resigned from City Council in 2009 after seeking advice from the Ohio Ethics Commission.
Incline District Development
Cranley worked to restore the historic Incline District of East Price Hill. He developed a $5 million project which consists of condominiums and a restaurant.
Ohio Innocence Project
In 2002, Cranley co-founded the Ohio Innocence Project at the University of Cincinnati College of Law and served as administrative director from 2002–2006. As of March 2019, the Project had exonerated 28 wrongly convicted individuals. Cranley's argument before Ohio's 5th Appellate District Court led to the 2006 reversal of Christopher Lee Bennett's conviction of aggravated vehicular homicide. Bennett had served four years of a nine-year sentence before the Project was able to use DNA to help overturn his conviction.
Mayor Cranley previously served on the boards of the Freestore Foodbank, Mercy Hospital Foundation, and the Jesuit Spiritual Center. Cranley was named a 2014 Aspen Institute Rodel Fellow.