Yorkshire-born Captain Tom Moore said it was a "great honour" to receive the Freedom of the City of London in a virtual ceremony.
The ancient tradition is believed to date back to 1237 and today's (May 12) ceremony was the first ever to be conducted by video-link.
Second World War veteran Captain Tom was nominated for the honour after raising almost £33 million for the NHS by walking 100 laps of his garden before his 100th birthday on April 30.
He sat beside his daughter Hannah Ingram-Moore at home in Marston Moretaine in Bedfordshire for the ceremony, which was streamed on YouTube.
After reading aloud the declaration of a freeman Captain Tom was asked to give a "wave of the pen" to symbolically sign the document.
Captain Tom, who served with the Duke of Wellington's Regiment, was told that previous freemen of the City of London include the Duke of Wellington.
Others honoured with the status include Edward Jenner, the man who discovered the vaccination against smallpox, founder of modern nursing Florence Nightingale and Winston Churchill.
Captain Tom was granted the Freedom of the City of London after a specialnomination by William Russell, the Lord Mayor of the City of London, and Catherine McGuinness, policy chair at the City of London Corporation.
The Lord Mayor said:
Not only did Captain Tom raise money in his mission, he also raised the spirits of people across the country.
Captain Tom said: "Lord Mayor thank you very much for your very kind remarks. It's an honour to speak to you.
Captain Tom was applauded as the ceremony concluded, adding: "Thank you all very much.
"It's been a great honour for me, thank you all very, very much, thank you."