Paul Oettli was born on 6 December 1872 as the son of a teacher and farmer in Altenklingen in the canton of Thurgau.
After the premature death of his father in 1881, the Oettli family moved to St. Gallen, where Paul Oettli's mother opened a boarding house. In St. Gallen, Paul completed his school education and his teacher training.
After graduation, Paul Oettli initially taught German at ‘Gibraltar’, a boys' institute in Neuchâtel. As he did not enjoy working at the institute, he left the school after only one year. Instead, he worked as a private teacher in Italy and taught German and French at various boarding schools in England. In the summer of 1898 Oettli returned to Switzerland and worked for a short time as a holiday teacher and in St. Peterzell, as a schoolteacher. The following year he took up a position as Assistant Teacher for German as a Foreign Language at the newly founded business academy in St. Gallen (today University of St.Gallen (HSG)).
In 1903, Paul Oettli was appointed Head Teacher and eight years later Professor of German Studies, teaching German and English at the business academy. In 1926 he was elected to be president of the institution, which in the meantime had become a business college. The standard period of study was extended from four to six semesters and three new professorial chairs - Business Administration, Economics, and Law - were established. The school changed its name once again at this time with the modern addition of ‘Hochschule für Wirtschaftswissenschaften’ to the already existing name ‘Handelshochschule St.Gallen’.
In 1928, Oettli introduced an annual celebration known today as Dies academicus, which was intended to make the citizens of St. Gallen more aware of the school, and founded the first alumni association in 1931, known today as HSG Alumni.
Paul Oettli was held in high esteem by his colleagues and students. Being an ardent scholar of the German language, he had a reputation of a passionate guardian of the German language. He was particularly interested in Swiss-German family names and names of places, and published a monograph on each of these topics.
Paul Oettli was known in wider circles through his journalistic work, among others in the NZZ, the Sprachspiegel, the Schweizerische Lehrerzeitung and the St.Galler Tagblatt. Oettli was also a member of an association for the German language which is known today as Swiss association for the German language (SVDS) and founded the St.Gallen German Lan-guage Society in 1911.
After his retirement in 1940, Oettli was appointed Honorary Professor.
Paul Oettli died on 29 February 1952 in St. Peterzell.