The Equality Bill -- which unites the various strands of diversity legislation, outlaws age discrimination and requires businesses to report on the gender pay gap -- will now face final consideration by the House of Commons prior to receiving royal assent.
It is expected to become law before the general election expected in early May.
The House of Commons will consider the amendments suggested by the House of Lords on April 6.
Amendments made by the House of Lords included a power to outlaw discrimination on the basis of caste; a ban on asking for health and disability information prior to making a job offer; and removing the ban on civil partnership ceremonies taking place in religious premises.
There has been mounting evidence of the prevalence of caste-based discrimination among people with origins in the Indian sub-continent.
After refusing to amend the laws for some years on the
ground that there was no evidence of such practice in Britain, the government has now accepted that discrimination on grounds of caste may be happening.
Harriet Harman, Minister for Women and Equality, said: "I'm pleased that the Equality Bill has completed its third reading in the House of Lords. This is a historic piece of legislation that contains a range of new rights, powers and obligations to help the drive towards equality, including tackling the overarching inequality caused by where you are born and what your parents do for a living."
The third reading is the final stage at which a bill can be amended before it becomes law.
Baroness Thornton has commissioned the National Institute of Economic and Social Research to conduct research into the subject.
Based on the evidence and research presented in the report, the government is expected to amend equality laws and initiate measures to prevent caste-based discrimination in the same way as discrimination on grounds of sex, colour, religion, age and sexual orientation.
Lord Avebury, who belongs to the Liberal Democrats group, had moved the amendment to the Equalities Bill 2009, and said he believed the research would "conclusively prove that caste discrimination does occur in the fields covered by the bill".
Keith Porteous Wood, Executive Director of the National Secular Society, said: "The blight of caste discrimination, under which millions in India are regarded as 'untouchable', has spread to this country virtually unnoticed."
In November 2009, research conducted by academics at the universities of Manchester, Hertfordshire and Manchester Metropolitan University said tens of thousands of people with origins in the Indian sub-continent faced caste discrimination in Britain.
The new study, whose main conclusion is that there is considerable evidence of caste-based discrimination among the Asians in Britain, was coordinated by the Anti-Caste Discrimination Alliance (ACDA) and included academics from three universities.
The report, titled 'Voice of the Community A Study into Caste and Caste Discrimination in the UK', says that the caste system is widespread and that it affects tens of thousands of people in the workplace, the classroom and even the doctor's surgery.
The study says: "There is clear evidence from the survey and the focus groups that the caste system has been imported into the UK with the Asian diaspora and that the associated caste discrimination affects citizens in ways beyond personal choices and social interaction.
"There is a danger that if the UK government does not effectively accept and deal with the issue of caste discrimination the problem will grow unchecked."