During the Polish-Soviet War, he volunteered for the 36th Regiment of the Academic Infantry Legion, a formation composed of university students and was decorated for his service.

He worked as a lawyer and attorney for the Polish Society of Authors and Composers (ZAIKS) where he specialized and excelled in copyright law.

His poetry was written mostly in the melodic style of the 8-syllable accentual verse, the most popular rhythmic structure among the Polish stylistic variations.

Among his most popular works is Chrząszcz (The Beetle), a poem proverbial for containing one the hardest-to-pronounce phrases in Polish literature.

Brzechwa also wrote a long-running series of children's books based on the adventures of Pan Kleks, the headmaster of a magical academy, and his students.