Mujahid Arshid killed Celine Dookhran in a jealous rage by slitting her throat and then dumped her body into a freezer, the Old Bailey court here was told during the trial.
Judge Justice Anthony Edis ordered him to serve at least 40 years behind bars before being considered for parole.
The builder from London was also found guilty of the attempted murder of a second 21-year-old Indian-origin woman, who was a friend of the victim and managed to escape with serious injuries during the attack last year.
Arshid was also convicted of sexual assault charges against the unnamed second woman between 2008 and 2010.
"He molested Celine's body while she was dead and then he molested me thinking I was dead. He's such a psycho," the woman, who cannot be named for legal reasons, said in her testimony from behind a curtain.
"I started saying things he wanted to hear 'I love you, we can run away together, we can be happy together, we can have a family'," she told the jury to explain how she was able to get away.
She later took to the stand to present her victim impact statement, recounting how "flashbacks and nightmares" prevent her from moving on and that her physical scarring from the attack was a "constant reminder of what Celine and I went through".
A statement from Celine Dookhran's mother, Iman, was also read out in court, in which she said her daughter "fell victim to pure evil" and that "coming to terms with her death is likely to be a lifelong assignment".
"She will always be in the darkness that surrounds us," her statement said.
In what was described as an "honour killing", prosecutors said that Arshid took advantage of the fact that Dookhran s step-father disapproved of her Libyan Muslim boyfriend, and told her she should be with a Muslim from Pakistan.
Arshid, said to be "sexually fixated" with both women, took advantage of the disputes by kidnapping them and making it appear like they had run away together.
While Dookhran, a Barclays bank worker, was found dead by police, the second woman managed to raise the alarm and was rescued by Arshid's brother, who saw her in the back of his truck and took her to a hospital where she went on to have two operations as she recovered from knife wounds.
From her hospital bed, she told police officers where they would find Dookhran's body in a freezer.
"He brought Celine down in a bag, picked her up and put her into the chest freezer," she told the court.
Arshid had claimed in court that it was the second woman who had killed Dookhran and shouted "I will prove that lying b*tch wrong" from the dock as the guilty verdict was read out in court.
Meanwhile, co-defendant Vincent Tappu an labourer employed by the builder was acquitted of all charges against him, which included the kidnap of both women, false imprisonment and possession of a firearm with intent.
The 28-year-old was in tears as he expressed his thanks to the jury over the verdict.