The inquiry by MPs and peers found alarming evidence of patients left lying in soiled bedclothes, sexual assaults, malnutrition, bullying and inappropriate use of medication.
It condemns the ill-treatment as a "serious and severe human rights abuse" and a "betrayal of trust".
In some circumstances, the report says, it was clear that a "criminal offence" had been committed.
The inquiry also criticises the lack of dignity with which people are treated, particularly the absence of privacy on mixed sex wards.
The Joint Committee on Human Rights condemns the Government for failing to provide "leadership and guidance" and says an "entire culture change" is needed to transform the system.
Existing legislation does not provide enough protection.
Following a House of Lords ruling that private care homes do not come under the Human Rights Act, the report calls on ministers to rewrite the regulations to ensure that all care homes are covered.
There should also be a "positive duty" on hospitals and care homes to "promote equality for older people".
The 102-page report offers a bleak picture of the conditions many elderly people have to endure.
It highlights how one 80-year-old woman in a care home was sexually assaulted by another resident but her daughter was not told about the attack until a year later.
People also reported how elderly relatives were left "slowly starving to death" because staff would not help them to eat. Many patients are routinely treated with a lack of dignity.