Nearly a quarter of the top 100 gay-friendly employers are banks and government departments, according to a list compiled by lobby group Stonewall.
Staff groups like the Gay Police Association were seen as positive
The number one employer in the group's first 'Corporate Equality Index' was the British Council.
Each was ranked according to various criteria such as equality policies and numbers of senior openly gay staff.
Citigroup, Credit Suisse First Boston, IBM, and Manchester City Council all came joint second.
The index would give the 1.7m lesbian, gay and bisexual people in the UK's workforce the chance to choose a gay-friendly employer, said Stonewall's chief executive Ben Summerskill.
"Gay staff still face a pink plateau in many British workplaces," he said.
GAY-FRIENDLY TOP 10
1. British Council
2. Credit Suisse First Boston
2. Manchester City Council
6. Department for Constitutional Affairs
7. Department for Education and Skills
7. Goldman Sachs
7. Inland Revenue
7. Nottingham Primary Care Trusts
But the organisations in the top 100 had demonstrated a "clear commitment" to meeting the needs of gay staff and customers, he added.
The list included 12 FTSE 100 companies and 12 government departments, as well as 21 local councils.
The emergency services fared well, with rankings for Strathclyde's fire brigade and police force, the Metropolitan Police, Lancashire Fire and Rescue Service, Sussex Ambulance Service and a number of NHS trusts.
Among retailers, B&Q, Marks & Spencer, Tesco, Co-op Group and Boots were listed in the top 100.
Sir David Green, director-general of the British Council - named top employer for 2005 - said they were "thrilled".
"This recognises the work the British Council has undertaken to promote equality and diversity...both in the UK and around the world," he said.
General Secretary of the Trades Union Congress (TUC) Brendan Barber, said it was "vital" that expert monitoring of employers' good practice on equality issues continued, with "maximum positive impact".
Research carried out for Stonewall in 2004 by the University of Cardiff found one in four lesbian, gay and bisexual people in Wales had at some time been dismissed or forced to leave a job because of their sexual orientation.
One in five gay employees still felt unable to come out at work, it found.