Bier began his residency in 1888 at the surgical clinic at the University of Kiel, under the mentorship of Friedrich von Esmarch.

[5] After professorships in Greifswald and Bonn, Bier was appointed Chief Surgeon and Geheimrat Professor of Surgery at the Charité - Universitätsmedizin.

[6] On 16 August 1898, Bier performed the first operation under spinal anesthesia at the Royal Surgical Hospital of the University of Kiel.

During the efforts to fit the syringe into the hub of the needle, a great deal of cerebrospinal fluid escaped, most of the cocaine to be injected was lost, and the spinal anesthetic was consequently a complete failure.

The profound anesthesia of his legs was demonstrated using increasingly painful stimuli, including a needle inserted down to the femur, a blow with an iron hammer to the shins, forceful avulsion of pubic hair, and "strong pressure and traction" to the testicles.

Hugo Stinnes (a business magnate and politician who was among the wealthiest men in the world at that time) died on 10 April 1924, about a month after Bier performed a cholecystectomy on him.

[9] On 24 February 1925, Bier performed an appendectomy on Friedrich Ebert, the first President of Germany,[10] who had signed the Weimar Constitution into law in 1919.

Bier is also considered to be a pioneer in the field of sports medicine, having played a pivotal role in establishing it as a discipline.

[13][14] Bier served as director of the Deutsche Hochschule für Leibesübungen ("German University of Physical Education") in Berlin from its founding in 1920 until 1932.

Gebhardt expanded on Bier's methods, adopting an academic approach to sports medicine and awarding degrees.