The history of Phra Phuttha Kosai began in 1955 AD (B.E. 2498), initiated by Mr. Chun Nok-kaeo, the Governor of Phrae, along with the Sangha and local citizens to create a provincial Buddha image blending Chiang Saen and Sukhothai styles. The casting took place at Wat Phra Bat Ming Muang Worawihan over three days and nights, starting April 22, 1955. During the ceremony, a miraculous light rain fell despite being the dry season, bringing joy to the devotees. Sacred Buddha relics, granted by the Supreme Patriarch, were later enshrined in the statue's head. The name "Kosai" honors the ancient name of Phrae, symbolizing victory and the auspicious spirit of the city.