Born in Warsaw, after four years of studies, Andrzejewski left Warsaw University without a degree. Attempting to continue his studies in France, He went to Paris in 1931. In August 1934 he married, but left his wife on their wedding day. After 1935 he underwent a religious conversion which led him to write Lad serca, which won an Award from the Polish Academy of Literature.

During the war Andrzejewski took part in the Polish resistance movement. In 1942 he fell in love with the lyrical poet Krzysztof Baczyñsky, but he didn't reciprocate Andrzejewski's love, although the latter claimed that Baczyñsky remained forever "the greatst love of his life".

After WWII he supported the communist government, but his support began to wane in the early 1950s, and in 1956 he stood on the side of the democratic opposition.

Homoerotic motifs, which can be found in his early short stories, and are overtly present in his last novel. Altough decidedly an active bisexual, he was marrie with two children and certainly not a gay activist.