Piyachat graduated from Chulalongkorn University in 1992 with a B.A. degree majoring in Mandarin. After graduation, she worked at Chia Lee Intertrade Co. Ltd., a company in C.P. Group, as a project coordinator. In 1993, she joined Yonok University, Lampang, as an officer in Mandarin Department. Her responsibilities were to assist Chinese professors with all paper works and to coordinate activities of the department in Chinese festivals. During the summer of 1994, she was one of the staff who led senior students of the department to take an intensive Mandarin course at Shantou University, China.

Afterwards, she furthered her study at Faculty of Social Sciences and Humanities, Mahidol University, and graduated in 1999 with a master of social sciences degree.

During 2000-2003, Piyachat was employed as a secretary of TUCED-SLUSE Project, a Danish government granted project of Thai Universities Consortium on Environment and Development-Sustainable Land Use and Natural Resource Management, of which the office of secretariat was located at Kasetsart University. Her scope of work mainly was to coordinate with Kasetsart University, Chiang Mai University, Maejo University and Royal Forest Department for the development of master and doctorate degree programs and human resources on SLUSE.