DETROIT—Michigan's governor on Thursday named a financial overseer of Detroit, who said his turnaround work could be completed in as little as six months if all the stakeholders in the troubled city work together.

Kevyn Orr, a bankruptcy attorney and partner at the law firm Jones Day in Washington, D.C., was named Detroit's emergency financial manager, a role that will give him sole, sweeping power to map the future of the city of roughly 700,000 residents. Republican Gov. Rick Snyder said he picked Mr. Orr for his interpersonal...