Nasser Masood Khokhar was jailed for 12 years for a series of sickening attacks on two women he befriended in the city's red light district by supplying them with drugs before moving them into his homes.
But the 35-year-old, from South Road, Walkley, then turned violent and left the women so terrified of his outrages they were afraid to leave.
Their plight only came to light when detectives were investigating another case involving sex attacks on prostitutes, and the women spoke out about their ordeal.
Det Con Matthew Bolger, who investigated the case, branded Khokhar "sadistic", "dangerous" and "a nasty piece of work" and said he was horrified to discover what the women endured. Khokhar was convicted of causing one of his victims actual bodily harm and raping the other four times and forcing her into sexual activity without her consent.
He moved his first victim into a flat in Upperthorpe in January 2004.
Khokhar attacked her when she returned home 10 minutes late. He struck her in her face, breaking her nose.
Sheffield Crown Court heard the woman was left disfigured for life because she was too frightened of Khokhar to seek medical help afterwards.
Khokhar moved his second victim into his Walkley home this January, forcing her to continue selling her body on the streets before returning home to be abused by him.
DC Bolger said: "He saw these women as nothing more than commodities to earn him money - he had complete disregard for them as people and their welfare and abused them for his own sexual and violent gratification.
"He controlled them both to such an extent that they were terrified of doing anything else but what he said.
"He seemed to target particularly vulnerable people to befriend.
"He would supply them with crack cocaine - although he was never charged with this - and ask them to move in with him."
He added: "The police would like to pay particular tribute to the victims who showed tremendous courage and determination in coming forward and going through with the trial."