Falleni was born in Italy, near either Livorno (according to family accounts) or Florence. Assigned female at birth, Falleni was the eldest of 22 children, of whom seventeen survived childhood. He migrated with his parents to Wellington, New Zealandc. 1877, at age 2. His father, a stern disciplinarian, worked as a carrier with a horse and cart and as a fisherman, among other occupations. After repeatedly dressing in male attire to obtain work in brickyards and stables during his teenage years, Falleni married in September 1894, but soon learnt that his husband was already married, and in 1895, Falleni left  New Zealand and began working on a ship, possibly as a cabin boy. His family made little effort to find him after years of being opposed to his behaviour.
According to a speculative account, Falleni later recounted that after less than two years at sea, he inadvertently disclosed during a drunken conversation with the ship’s captain, a man named Martello, that he had been raised as female: speaking in Italian, Falleni stated that his grandmother referred to him as a piccolina (the feminine form of the noun for ‘little one’). Although there is no proven evidence for this, Falleni was also ostracised by the rest of the crew and repeatedly raped by the captain. Falleni was put ashore pregnant and destitute in 1898, at the ship’s next port of call in Newcastle, New South Wales.
In Sydney, Falleni gave birth to a daughter, Josephine Crawford Falleni, and put the child into the care of an Italian-born woman, Mrs. de Angelis, in Double Bay. He took on the male identity of Harry Leo Crawford, of supposed Scots descent, visiting his daughter only infrequently. Josephine Falleni called de Angelis ‘Granny’, who told her that her father was a sea captain.
In 1912, after a series of manual jobs in abattoirs, pubs, and in a rubber factory, Falleni entered the employ of a Dr. G. R. C. Clarke in Wahroonga, Northern Sydney, as a general useful and sulky driver. It was there that he met Clarke’s housekeeper Annie Birkett, who had been widowed several years before, with a son named Harry Birkett. Birkett and her son left for Balmain, where she used some money she had to set up a confectionery shop. Falleni followed her there and took an interest in the business. On 19 February 1913, Falleni and Birkett were married at the Methodist parsonage in inner city Balmain. Soon after, the couple moved to Drummoyne, where Falleni worked in hotels and factories at various kinds of work.