Officers made the grim discovery after attending an address in Holbeck Road, Hanwell, shortly after 4.30pm on Sunday, amid concerns for the welfare of a woman there.
Police forced their way into the property and found the body.
The Met police has named the deceased as 35-year-old Shakira Spencer, who lived at the address.
A special post-mortem examination was set to take place on Wednesday at Uxbridge Mortuary.
A murder investigation has been launched by homicide detectives from the Met’s Specialist Crime Command. Three people - a man and two women - have already been arrested on suspicion of murder.
Detective Chief Inspector Brian Howie said: “While we await the outcome of a post-mortem examination to confirm how Shakira died, all the information available points to the fact she has come to harm. I need to know why people would want to harm Shakira.
“I am appealing for any information about Shakira specifically in the period between Friday, 9 September and Friday, 16 September. Did you see her out and about? Did you have contact with her in any way? If so, did she speak about any concerns she had? I would urge anyone with information, no matter how insignificant you think it may be, to get in touch with my team.
“I also want to hear from anyone who knew Shakira in any capacity. We need to build a comprehensive picture of Shakira’s life so we can begin to understand who might have wanted to harm her.
“This is a fast-moving investigation and arrests have been made but it is vital we gather as much relevant evidence as possible.
“Specially trained officers are supporting Shakira’s family at this devastating time but they need answers and I would implore anyone who can assist to get in contact with police. If you don’t feel comfortable speaking directly to us, then you can contact the independent charity Crimestoppers – 100% anonymously – with what you know.”
Detective Superintendent Sharon Brookes of the West Area Command Unit, which covers Ealing, said: “I understand the alarm and concern this news will cause the local community in Hanwell where Shakira lived, and throughout the wider Ealing borough.
“A team of experienced detectives are now working diligently to ensure those responsible for this crime are identified and held to account.
“Local residents will see increased police activity around Holbeck Road – please don’t be alarmed as this forms part of our response to such a serious incident. Officers from Ealing will also be in the area to provide reassurance and answer any questions residents may have; I would ask anyone with concerns to speak to them or contact your local Safer Neighbourhoods Team.
“If you have information that could assist the investigation then please get in contact with police immediately.”
On Monday, police arrested three people on suspicion of murder: a 25-year-old man and two women aged 37 and 43. The three have been taken into custody.
Two people – a man aged 40 and a 78-year-old woman – have been arrested on suspicion of assisting an offender. Both have been bailed pending further enquiries.
Anyone with information that may assist the investigation is asked to call police on 101 or tweet @MetCC and quote ref 59/26SEP. You can also provide footage and images here.
If you have information, but don’t want to talk directly to police, you can contact the independent charity Crimestoppers on 0800 555 111 or via crimestoppers.org