The congratulations come from people from preschool age to residents of nursing homes, and he thanked everyone "from the bottom of his heart", according to The Guardian.
The day will be marked with an event from the Royal Albert Hall in London, broadcast live by the BBC. The programme will feature music from his programmes, as well as stories and reflections from public figures and leading conservationists.
Attenborough was born in the UK in 1926 and began his long career at the BBC in 1954. Today he is one of the world's most famous narrators.
