[2] Napoleon Cybulski was born on 14 September 1854 in Krzywonosy, in the Vilna Governorate of the Russian Empire (present-day Belarus).

His father was Józef Napoleon Cybulski, of the Prawdzic coat of arms, and his mother was Marcjanna Cybulska, née Hutorowicz.

In 1885 he obtained the degree of Doctor of Medicine with a thesis on the velocity of blood flow as detected by a photohemotachometer, a device he had constructed himself.

His students included Adolf Beck, Władysław Szymonowicz, Leon Wachholz, Aleksander Rosner, and Stanisław Maziarski.

He married Julia Rogozińska and opened a dental surgery office in order to satisfy the financial needs of his large family.

Under Cybulski's supervision, Beck made pioneering studies of cerebral-cortex activity in response to peripheral-nerve stimulation in dogs and monkeys, using electrodes placed on the skull to record changes in electric potential.

He gave a description of the difference between afferent and efferent impulses entering and leaving the spinal cord based on recordings from dorsal and ventral roots.

Some of his theses in O hypnotyzmie ze stanowiska fizyjologicznego (On Hypnosis From the Physiological Standpoint) anticipate ideas of Sigmund Freud and make him a precursor of the concept of the unconscious.

[14] Apart from medicine, Cybulski was also interested in a range of social questions and published books and articles such as Czy państwo i społeczeństwo mają obowiązek popierać naukę?

In 1896, Cybulski, a pioneering Polish bacteriologist, Odo Bujwid (1857–1942), and social activist Kazimiera Bujwidowa, established the first girls' gimnazjum (secondary school) in Kraków.