"My family joins me in sharing the difficult news that Gerald Ford, our beloved husband, father, grandfather and great-grandfather, has passed away at 93 years of age," Betty Ford said on Tuesday.
"His life was filled with love of God, his family and his country."
A former Republican congressman, Ford took office vowing "our long national nightmare is over".
He served for 2 1/2 years with a style often mocked as bumbling until he lost the 1976 presidential election to Jimmy Carter.
Not elected
Ford had been ailing and largely out of the public eye for several years.
He was the only US president who was not elected to either the presidency or vice presidency. He was appointed vice president in 1973 after Nixon's vice president, Spiro Agnew, resigned to avoid prosecution on corruption charges.
When Nixon resigned on August 9, 1974, to avoid impeachment in the scandal over a politically motivated burglary of Democratic Party offices in the Watergate complex in Washington, DC, Ford became president.
He had served 26 years as a congressman from Michigan.
Despite Ford's reputation for decency, critics ridiculed his occasional clumsiness with barbs such as "he can't walk and chew gum at the same time".
His wife, Betty Ford, became a national figure in her own right as an outspoken crusader against drug and alcohol addiction.