Sabah Khan, 27, cut the throat of mother-of-four Saima Khan, 34, while the victim's children were sleeping upstairs at the family home in Luton.
At the time of the savage attack other members of the family were at a local mosque attending a funeral.
Saima Khan, who was also a care worker, moved to England from Holland lived with parents, sister and taxi-driver husband Hafeez Rehman and was described by neighbours as a 'quiet but friendly lady'.
She was found slumped in a pool of blood in the hallway of her semi-detached home at around 11.30pm on 23 May last year.
Detectives sent to the scene of the murder initially investigated claims a burglar had broken into the property and carried out the killing.
Sabah Khan stood in the dock of the Old Bailey today to plead guilty to murdering her sister.
Sabah will be sentenced on Thursday.
Judge Christopher Moss QC told her: 'You will appear before this court again on Thursday at 10am and you must remain in custody.'
|The scene of the incident|
After the case the senior investigating office, Detective Inspector Adam Gallop described the horrific murder as 'a horrific crime.'
Shortly after her death Mrs Khan's husband Hafeez paid an emotional tribute to his wife.
He said: 'She was a loving mother to four beautiful children, a devoted wife, a beloved daughter and the most caring of sisters.
'She has been taken from us at the age of 34 and my children have been deprived of their mother.
'This was a junction in our lives where we intended to watch our children grow, to love them and spend quality time as a family and make memories.
'We have been left with a gap in our lives and we can only pray that she is resting in peace.
'As everyone can appreciate and understand that the circumstances have torn our hearts apart.
'My family and I would like to thank you all for the condolences messages, and support that we have received from family, friends and the local community.'
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