A 10-strong panel of experts highlighted what it said were Washington's breaches of the agreement ratified by the United States in 1994.
The UN Committee against Torture, which monitors international compliance with the UN Convention against Torture, has called for the abolition of electric shock stun-belts and restraint chairs on prisoners, as well as an end to holding children in adult jails.
It also said female detainees are "very often held in humiliating and degrading circumstances" and expressed concern over alleged cases of sexual assault by police and prison officers.
The panel criticised the excessively harsh regime in maximum security prisons, the use of chain gangs in which prisoners perform manual labor while shackled together and the number of cases of police brutality against racial minorities.
"The committee expresses its concern about the number of cases of police ill-treatment of civilians and ill-treatment in prisons.
"Much of this ill-treatment by police and prison guards seems to be based upon discrimination," the report said.
US reaction
A US official told the panel that the US Government would give the report "very close and careful consideration".
The United States is often regarded as the guardian of global human rights, but it says that while its record on preventing torture is far from perfect it is still one of the best in the world.
Last week, the US Assistant Secretary of State for Human Rights, Harold Koh, said stun belts were only used to prevent escape, loss of life or grievous bodily harm.
"My own view is that they're being used completely within the law," he said.
Mr Koh rejected claims that Washington set its own standards for deciding whether it had committed torture.
This is the first time the United States has been put in the dock before the Geneva-based body.
Report welcomed
The human rights organisation, Amnesty International, welcomed the UN recommendations, saying it was time the US ended its "pick and choose" approach to international law.
"It's a strong message to the United States that once you ratify these treaties you have to do so in the same way that everybody else does," Rob Freer, a spokesman, said.
Mr Freer also welcomed the call for stun belts to be abolished, saying that according to Amnesty International, more than 1,000 were in use around the United States.
He claimed the remote-controlled belts have been activated on at least 30 occasions.
In a report to the committee released last week, Amnesty criticised brutality, beatings and shootings by US police officers, sexual abuse of female prisoners and cruel conditions in isolation units.
The two-day examination by the UN commission of the United States' record followed fatal police shootings of unarmed black suspects in New York and Los Angeles.