A survey of 2,000 adults by recruiter Randstad found that a third of people in the UK planned to retire early.
Three out of four of those interviewed also believed there was pressure for older workers to retire at state pension age.
Those planning early retirement said they felt they would not be wanted by their employers when they were older.
Mark Bull, chief executive of Randstad, said: "The baby-boomers are nearing retirement, and we could have a huge skills shortage on our hands if these senior, established staff exit the workforce en masse.
"This additional squeeze on skills could be catastrophic - especially considering the current war for talent. Given the current skills gap, finding the right people for the right jobs is becoming increasingly difficult.
"Now more than ever employers should hold on to their high performers as tightly as they can, as it can take a long time to fill the gap left by senior staff when they leave."
Those in Belfast, Liverpool and London were most likely to retire early, according to the research.
TUC general secretary, Frances O'Grady added: "This report is a reminder of how important it is for government and industry to plan for the long term.
"This planning must include significant investment in the skills and development of workers - both as part of the government's industrial strategy, and in the business strategy of any company that wants long-term success."
Pensions minister Ros Altmann said: "Employers should cast aside out-dated thinking and embrace the reality - older workers bring talent, loyalty and enthusiasm to the workplace and have a vital role to play in our economy.
"Working longer can bring many benefits to individuals and businesses and, with an ageing population, it is important that people do not feel pressured into stopping work before they are ready."