Police have named the 80-year-old woman, who was stabbed to death at her home in Manor Park, as Shotera Bibi.
Detectives have arrested a man in his 30s, who knew the victim, with Scotland Yard saying he remains in police custody.
Just before 10am on Saturday, police found Ms Bibi in her home in Landseer Avenue with stab injuries.
The London Ambulance Service and Air Ambulance tried to save her, but she was sadly pronounced dead at the scene.
Police launched a murder investigation, and found the man in his 30s while searching the surrounding area.
He remains in police custody.
Scotland Yard said Murder Squad is leading the investigation from the Specialist Crime Command.
Ms Bibi’s family have been informed and a post-mortem examination was carried out yesterday.
Any witnesses or anyone with information that may assist the investigation are asked to call 101, ref 2126/02apr.