Tadeusz Boy-Żeleński also made a name for himself as a brilliant and accurate translator of the French Literature. This is how he commented on the beginnings of this career as a translator:
I longed for Paris; I missed that wonderful smile of France, its witty but profound wisdom, its breath of love. I started experiencing a vague need to (...) create an imaginary France in my study, something similar to what is now fashionable in medical studies and known as the artificial heart. So, I took up translation.
Aside the works of the representatives of the Symbolist movement, French literature was not in the centre of attention of the Polish Modernists. As he incessantly remained in strong opposition to the style of the Young Poland movement, Boy would read the moralists and satirists of the Enlightenment period, classical comedies of the Molière's era as well as the realist novels of the 19th century.
He first reached for Molière and Balzac, two authors closest to his interests. As early as in 1909, Molière's The Misanthrope and The Forced Marriage translated by Boy were staged at the Słowacki Theatre in Kraków; the same year his translation of Balzac's Physiology of Marriage was published. Between 1909 and 1912 the writer completed the translation of the entire oeuvre of Molière, which was released as a six-volume publication of Works (Lviv 1912).
Two years later, the writer was awarded by the French Academy in recognition for his work. In that year, he also translated Lives of Fair and Gallant Ladies by Brantôme, which again pigeonholed him as the "scandalmonger" and "erotomaniac"; five volumes of Rabelais; the first volume of Confessions by Rousseau, Comedies by Marivaux, Discourse on the Method by Descartes, as well as started rehearsing Essays by Montaigne.
During World War I when he used to work as a military doctor, Boy came up with the idea of establishing a library consisting of his own translations: there was an inscription saying "the Library of Boy" and the catalogue number on the title page of each of the works that he translated. Finally, there were over one hundred such volumes published.
In 1922, Wacław Borowy complimented on Boy's achievements in the field of translation in his articles Boy jako Tłumacz (Boy as a Translator) and Oryginalność w Przekładach Boya (Originality in Boy’s Translations) by appreciating the translator's contribution to the promotion of the French literature. Aside his translating achievements, Boy is also the author of historical texts and critical essays on literature as well as biographies of French writers - including Studia i Szkice z Literatury Francuskiej (Critical Studies and Sketches of French Literature); Molier Życie i Twórczość (Molière. Life and Works); Balzac.
Above all, however, Borowy admired the artistic value of translations and the ability to convey the spirit of the translated work. In the critic’s opinion, Boy's genius lied in his ability to create the language and style of Polish Classicism for the purpose of expressing the French Classicism. He succeeded in conveying the meaning of a given work not only through its content, but also the rhythm, melody, tone, and syntax. In 1958, Jan Błoński called him "the Shakespeare of translation".
Beginning with 1919 Boy translated mostly Balzac and Stendhal. At the end of "the love affair with France" which lasted until 1939, he completed numerous translations including: In Search of Lost Time by Proust, Ubu Roi by Jarry or The Vatican Cellars by Gide. The mentioned works differ considerably from the clearly marked literary preferences from the Library of Boy.
For the most part, the translator chose such authors who advocated the classical transparent form and rationalism. Thus, he reached for the French encyclopedists: Diderot, Voltaire, Montesquieu and Rousseau; the Renaissance authors such as Villon or Montaigne; representatives of the 17th century including Descartes, Pacal, Molièr; and finally for the great realist writers: Balzac and Stendhal.