The Queen frontman's home in the suburb of Feltham was decorated with a English Heritage Blue Plaque, a historic marker that ties the location with a famous person, reported Entertainment Weekly.
Blue plaques have been put in the English capital for 150 years and currently total over 900. English Heritage, the organization that awards the plaques, only adds a dozen or so each year.
The plaques have become popular tourist destinations. The inscriptions list the honoree's name, date of birth and death, and occupation.
The ceremony featured Queen guitarist Brian May and Mercury's sister, Kashmira Cooke, unveiling the plaque.
"Mum and I are so proud and pleased that English Heritage is honouring our Freddie with a Blue Plaque, and that he will be amongst other famous names forever. Secretly he would have been very proud and pleased too," Cooke said.
Mercury's parents purchased the Feltham, London home in 1964. The musician met May and fellow future Queen bandmate Roger Taylor while living there. They formed Queen in 1970.