Kollros, the son of a baker, was from 1896 as a student of mathematics and physics at the Zurich Polytechnikum, where he was a fellow student of Albert Einstein and Marcel Grossmann. After graduating in 1900, Kollros taught mathematics from 1900 to 1909 in secondary school in his hometown of La Chaux-de-Fonds. In 1903–1904 to 1909 he studied in Göttingen with Hermann Minkowski and David Hilbert. From 1904 to 1909 Kollross was a privat-docent (lecturer) at the University of Neuchâtel. He received his doctorate in 1905 from the University of Zurich with thesis advisor Hermann Minkowski and thesis Un algorithme pour l'approximation simultaneé de deux grandeurs. At ETH Zurich, where Marcel Grossmann taught until 1927 in the same field, Kollross held from 1909 to 1948 the francophone chair of géométrie descriptive et de géométrie euclidienne.
In 1940–1941 he was president of the Swiss Mathematical Society and from 1958 an honorary member of the Society. He was president of the Steiner-Schläfli committee (tasked with the publication of their works). In this role, he was co-editor of Schläfli's collected works (3 vols.,1950–1956).
His doctoral students include Ferdinand Gonseth.
- Un algorithme pour l'approximation simultaneé de deux grandeurs, Imprimerie Soullier, Geneva 1905
- Géométrie descriptive, Orell Füssli, Zurich 1918
- Cours de géométrie projective, Griffon, Neuchâtel 1946, 108 p.
- Stammbach, Urs (31 March 2009). "Kollros, Louis". Dictionnaire historique de la Suisse.
- At that time there were parallel lectures in German and French. Kollros attended only the French lectures, as he mentions in his reminiscences published (in connection with a celebration held in Bern) for the 50th anniversary in 1955 of the theory of special relativity. Louis Kollros: Albert Einstein en Suisse: Souvenirs. In: Helvetica Physica Acta. Supplementum 4, 1956, pp. 271-281, and as a German translation: Erinnerungen eines Kommilitonen. In: Carl Seelig (ed.): Helle Zeit – dunkle Zeit: In memoriam Albert Einstein. Europa Verlag, Zürich 1956, pp. 17–31 doi:10.1007/978-3-322-84225-1_3
- Louis Kollros at the Mathematics Genealogy Project
- "Honorary Members of the SMS".