Millar, from Boston, in Lincolnshire, had struggled with a “cycle of addiction” the jury heard and was known to support workers in the area.
Singh, who the court was told had paid for sexual acts more than 100 times previously with different women, said he was “embarrassed” about his actions.
He had pleaded guilty to manslaughter, not murder, claiming her death was an accident, but during evidence admitted he knew she was already dead when he left her on the street.
Singh told the jury how he had also previously referred to women in derogatory terms.
Text messages shown to the court included messages such as “Van, Rope, Pills” when speaking to his friends about a woman on the internet who he had said was attractive.
Prosecutor, Rachel Brand KC suggested that “Perhaps [to Singh] a woman like her, a sex worker, is unimportant and disposable”.
“It was a violent attack on a slightly built woman in no position to fight back,” she said.
Although her death was caused by “manual compression of the neck” Millar was also found with multiple neck fractures and bruising across her face and body.
She is survived by family members, who sat through the trial with “quiet dignity”, said defence KC Gurdeep Chada.