Lapathiotis was born on October 31, 1888 in Athens, the only child of his politician father. He studied law in Athens but his inclination was towards poetry and writing. By 1907, his poems were already being published in magazines of that period.
In 1912 during the First Balkan War, Lapathiotis was conscripted into the Greek army. In 1914 he published his controversial "Manifesto" in "Noumas", a magazine of that era. Three years later, he published his poem "Kravgi" in "Rizospastis" and followed his father to Egypt where he met Constantine Cavafy. He returned to Athens shortly afterwards and continued to write poetry. However, his personality had drastically changed: he abused drugs and avoided being seen in public during the day, coming out only at night.
In 1939 his collection of poems was published but the poet had descended into poverty and depression largely due to his continued drug abuse. On January 7, 1944 Lapathiotis killed himself with a revolver. At his request, he remained unburied for three days to make sure he was dead. His funeral expenses were paid from a collection taken amongst his friends.