The pictures of Henry Bushnell were found by Prof Peter Stoneley, from the University of Reading, who carried out a study of Wilde's fellow prisoners.
He said the playwright had been "attracted to" Bushnell but details of their relationship were unknown.
Wilde was sentenced to two years' imprisonment for homosexuality in 1895.
In a letter the disgraced playwright mentioned a "little dark-eyed chap", believed to be labourer Bushnell, who was jailed for theft 21 times between 1892 and 1911, said Prof Stoneley.
Most inmates were not photographed but, as a repeat offender, Bushnell was. There are seven mugshots of him in the archives of the recently closed Reading Prison.
Speaking on the 160th anniversary of Wilde's birth, Prof Stoneley said: "We don't know the full details of the relationship between Wilde and Bushnell.
"However, Victorian prisoners were not officially even allowed to speak to each other while in prison - much less eat or work together, or form private relationships.
"What we do know is that as well as mentioning him in his letters, Wilde sent money to Bushnell after he was released from prison, although further meetings are unlikely."
Records about the execution of Charles Wooldridge, the soldier whose death is the subject of Wilde's work The Ballad of Reading Gaol, were also found in the archives.
In records that detail the execution of Trooper Wooldridge, the prison doctor noted that he had a "rather long" neck.
The study revealed details of the Victorian prison system, which Wilde went on to campaign against.
The Oscar Wilde and Reading Gaol exhibition opens at the Berkshire Record Office on Monday.
Photographs of the only working-class man Oscar Wilde took an interest in have been unearthed in a search of Reading Prison archives.