More than one million older people feel lonely and 250,000 have no friends or family, a Help the Aged survey says.
More than one million elderly spent Christmas alone
It said the "depressing" results show elderly people are increasingly sidelined by fast-paced modern lives.
Launching its Helping Unite Generations campaign, the charity said 9% went six months without seeing family members.
"We far too often shunt older people into the sidings of life, leaving them without enough money or activity, but above all human warmth," it said.
'Indifference and neglect'
The survey, carried out by NOP World, also suggested one in 10 over 65s see their grandchildren less than twice a year and 19% of those living alone will go more than a month without seeing any members of their family.
More than three million older people feel out of touch with the fast pace of modern life and 820,000 feel cut off from society, it added.
And although two million older people would like to have more social contact
with younger people only 32% had friends under the age of 30 who they visit, or are visited by.
Paul Cann, Help the Aged's director of policy, said its Hug campaign is set to run throughout April, with a nationwide street collection planned for Hug Day, 22 April.
Mr Cann said it aimed to unite generations and that it "challenges all our families, friends and neighbours to bring our oldest and frailest citizens in from the cold of our indifference and neglect".