Tammann was born in Yamburg (now Kingisepp, Leningrad Oblast). His father, Heinrich Tammann (1833–1864) was of Estonian peasant origin and his mother, Matilda Schünmann, was of German origin. Tammann graduated from University of Dorpat in chemistry. He came to Göttingen University in 1903 where he established the first Institute of Inorganic Chemistry in Germany. In 1908 he was appointed director of the Physico-Chemical Institute. His interests focused on the physics and physical chemistry of metals and alloys (metallurgy). In 1925, Tammann was awarded Liebig Medal. On 28 May 1936, Tammann was awarded the Eagle Shield of the German Empire (), with dedication "The Doyen of German Metallurgy". He was also known for the Vogel-Fulcher-Tammann equation, and the Tait-Tammann equation of state which seeks to account for the compressibility of liquids.
Tammann died in Göttingen at age 77.