Yonago is a city in western Tottori Prefecture, Japan, facing the Sea of Japan and making up part of the boundary of Lake Nakaumi. It is adjacent to Shimane Prefecture and across the lake from its capital of Matsue. It is the prefecture's second largest city after Tottori, and forms a commercial center of the western part of this prefecture. As of October 1, 2017, the city has an estimated population of 148,720 and a population density of 1,100 persons per km². The total area is 132.21 km².
It is home to the Yonago City Museum of Art. Kaike Onsen, which sits along the Miho Bay and is part of Yonago, is said to be the birthplace of the triathlon in Japan. Since the city has begun to develop into a trade center of note, it has acquired the nickname Osaka in San-in.