Prosecutors had asked Judge Harry Leinenweber to sentence him to 25 years – and to not let him begin serving those until after he completed the first 30-year sentence, imposed on him last year in New York.

“The nature of this offence is horrific,” Judge Leinenweber said in explaining the 20-year sentence. He noted that Kelly’s sexual abuse victims would suffer from his crimes for the rest of their lives.

At the same time, he accepted defence arguments that Kelly might not even make it to 80, so handing him a consecutive lengthy sentence, rather than allowing him to serve all but one year of it simultaneously, did not make much sense.

“He has a life expectancy of not a hell of a lot more,” the judge said. “He is 56 years of age.”

Kelly’s defence lawyer celebrated the ruling as a victory, and some of the singer’s fans could be heard cheering outside the courtroom.

Kelly remained still, his eyes downcast, as Judge Leinenweber explained what was at times a hard-to-follow sentence.

He did seem to show some emotion when a representative read a statement written by “Jane”, one of his accusers and a key prosecution witness.

“I was brainwashed by Robert and a sex slave,” Jane’s statement said. “It almost killed me.”

Kelly did not make a statement in court prior to the sentencing decision, heeding the advice of his lawyer, Jennifer Bonjean, to stay quiet while they appeal both his Chicago and New York convictions.

“It’s the right outcome,” Ms Bonjean said. “The judge was reasonable. He, I think, took into account both sides and ultimately was fair.”

The US Attorney in Chicago, John Lausch, conceded that prosecutors were disappointed Kelly did nt receive more consecutive prison time.

But he added, “Twenty years is a significant sentence, and we are happy that that was imposed in this case.”

The judge said at the outset of the hearing that he did not accept the government’s contention that Kelly used fear to woo underage girls for sex, a determination that was important in deciding whether to extend Kelly’s current term significantly.

“The (government’s) whole theory of grooming, was sort of the opposite of fear of bodily harm,” the judge told the court.

“It was the fear of lost love, lost affections (from Kelly)’. It just doesn’t seem to me that it rises to the fear of bodily harm.”

Two of Kelly’s accusers asked the judge to punish him harshly.

“When your virginity is taken by a paedophile at 14 – your life is never your own,” Jane’s statement read.

Another accuser, who used the pseudonym “Nia”, addressed Kelly directly in court. Speaking forcefully as her voice quivered, Nia said Kelly would repeatedly point out her alleged faults while he abused her.

“Now you are here – because there is something wrong with you,” she said. “No longer will you be able to harm children.”

Jurors in Chicago convicted Kelly last year on six of 13 counts: three of producing child porn and three of enticement of minors for sex.

Prosecutors did not get a conviction on the marquee charge: that Kelly and his then-business manager successfully rigged his state child pornography trial in 2008.

Kelly rose from poverty in Chicago to become one of the world’s biggest R&B stars. Known for his smash hit I Believe I Can Fly and for sex-infused songs such as Bump n’ Grind, he sold millions of albums even after allegations about his abuse of girls began circulating publicly in the 1990s.

Prosecutors described Kelly as “a serial sexual predator” who used his fame and wealth to reel in, sexually abuse and then discard star-struck fans.

US Assistant Attorney Jeannice Appenteng urged the judge to keep Kelly in prison “for the rest of his life”.

Kelly’s abuse of children was especially appalling, she said on Thursday, because he “memorialised” his abuse by filming victims, including Jane.

Ms Appenteng told the court Kelly “used Jane as a sex prop, a thing” for producing pornographic videos.

But Ms Bonjean has accused prosecutors of offering an “embellished narrative” to get the judge to join what she called the government’s “bloodthirsty campaign to make Kelly a symbol of the #MeToo movement”.

The singer has suffered enough, including financially, Ms Bonjean said. She said his worth once approached one billion US dollars (£840 million), but that he “is now destitute”.

Given his age and current 30-year sentence, Ms Bonjean said sentencing Kelly to 25 more years would be “overkill”.

“It is symbolic,” she said. “Why? Because it is R Kelly.”

Just before Kelly was taken back to detention on Thursday, he requested that he not be placed on suicide watch because constant checks by guards “is in and of itself cruel” and “creates mental health issues,” Ms Bonjean said.

“He was expecting this,” she told the judge. “Mr Kelly is not suicidal.”