There is no information about the early life of Armand Jerome, prior to his 'bursting upon Sydney like a brilliant meteor' in the early years of the 1890s, as one contemporary report phrased it. Jerome quickly gained the favour of numerous people in Sydney's theatre and bohemian circles by treating them to picnics and lavish suppers, and by passing as a relative of the British writer Jerome K. Jerome.
Jerome said he had come to Australia from a visit to America, and he was generally regarded as a worldly, talented man who could play the piano, speak several languages, and who 'dallied with literature now and then merely as a recreation'. He showed his commitment to literature by founding Cosmos Magazine in 1894. While in Sydney, Jerome lived at the elegant Australia Hotel, which stimulated the sense that he was a wealthy man. At first, his creditors were generous, but in 1896 rumours started spreading that he was an impostor. Soon after, one of his creditors denounced Jerome for forging some documents in order to borrow ten pounds, which led to the issue of an arrest warrant in July of that year. By this time Jerome had left his usual place of residence, and the authorities initially believed that he had fled New South Wales.
Some four months after the event, Detectives Goulder and Hinds followed leads that pointed to Jerome's hiding place in Liverpool, thirty kilometres from Sydney. After seeing Jerome walking in the street, one of the detectives approached him and escorted him to the boarding house where he had been living under a false name. Newspaper accounts of the event remark approvingly on Jerome's courteousness towards the detectives, the fact that he was clean shaven, and that he changed his linen before being taken into custody at the Water Police Court (now the Justice and Police Museum in Sydney).
Armand Jerome was charged with forgery and sentenced to three years' imprisonment.
Jerome married journalist, author and playwright Nellie Bruton (Helen Jerome) in Sydney in 1900.