Charity's chief executive Emer O'Neill said, "Depression is the biggest mental health challenge among working-age people could lead to loneliness and isolation at work. Many companies aren't properly equipped to manage employees who suffer from depression so providing support to these individuals in the workplace is essential."
The research, which involved 1,200 people, also said that employers needed to recognise the condition and support the affected staff.
Another report showed how firms such as Royal Mail, Barclays and Unilever are lending a helping hand to their depressed workers and also bringing about changes in their policies to provide support to their affected workers.
The survey also suggested that just 50 per cent of those who felt lonely or isolated had shared their feelings with a colleague, and 71 per cent found that discussing their condition with a colleague helped them feel better.
Tim Munden, vice-president of human resources at Unilever UK, said his company "firmly believed" in addressing the problem. "We aim for a 10 per cent reduction by 2015 in work-related mental ill-health cases and working days lost to mental ill-health," he said.
Ogilvy, the international advertising and PR firm, conducts lunchtime sessions on nutrition, sleep and time management, and when needed also makes available clinical psychologist to employees.