Tracey Burrows, 56, was supposed to carry out a 30-minute home visit to Julie Cleworth, 43, but instead went to see her own mother after she wrongly assumed she had not arrived back from a stay in hospital.
Burrows then rang her boss to say she had been inside the property in St Helens, Merseyside, and found no sign of Ms Cleworth.
Her lie meant her employers, Unite Healthcare Ltd, cancelled Ms Cleworth's care package because they thought she was still in hospital and left the housebound patient without food, fluids and medication before she was found dead four days later on February 9 2017.
Sentencing on Tuesday, Judge Neil Flewitt QC told Burrows: "Your neglect of Julie Cleworth set in motion an unbroken sequence of events which led directly to her death.
"I accept that you neither intended nor actually foresaw the consequences of your actions.
"However, if you had stopped to think about what you were doing, instead of neglecting your duty and going instead to visit your mother, you would have realised that your actions might lead to Julie Cleworth's death."
Expert evidence given at her trial last month at Liverpool Crown Court said Ms Cleworth would have suffered some or all of the following symptoms in the period leading up to her death: abdominal pain, vomiting, profound loss of energy, confusion, deranged conscious level and eventually coma.
Judge Flewitt noted: "One can only imagine the terror which must have overcome Julie Cleworth as she lay helpless in bed, realising that she had been abandoned and left to starve to death."
Burrows, of Sherdley Park Avenue, St Helens, had denied manslaughter by gross negligence, but a jury found her guilty.
In 2013, Ms Cleworth - who weighed 18 and a half stones and was classified as morbidly obese - suffered a stroke which left her completely immobile.
Living alone, she became totally reliant on care workers for her basic needs and required five visits per day to her home in Berwyn Grove.
A week before her death she was admitted to Whiston Hospital with suspected deep vein thrombosis but was discharged three days later.
Ordinarily Ms Cleworth spent all her time and slept on the sofa in the living room at the front of her home but the ambulance crew did not have the equipment to move her there so put her on an electric bed in a room at the back of the house, the court heard.
Burrows, who had been a regular carer for Ms Cleworth, wrongly assumed she was not home from hospital because there was no light coming from the front living room.
She did later return to the address later the same evening, but this time did not even get out of her car to check.
Judge Flewitt said it could properly be argued that Unite Healthcare should have made further inquiries to establish where Ms Cleworth was, but the defendant's neglect of duty and subsequent lie was the "catalyst" for what followed.
Burrows had worked for privately owned Unite Healthcare since 2013, although she was convicted of benefit fraud in March 2014 and received a 12-month jail term, suspended for the same period.
Nigel Power QC, defending, said the manslaughter offence was a lapse from the otherwise exemplary care the mother-of-three provided to all her patients and that an "eclectic" range of character references showed her to be "utterly selfless in almost every aspect of her life".
He noted she had expressed remorse and shame but Judge Flewitt said he found those sentiments "difficult to reconcile" with her assertion to the jury that she did not believe she bore any responsibility for Ms Cleworth's death.
The judge also referenced Burrows's pay, in which she received £7.20 per hour - the then national minimum wage.
He said: "It is surprising that as a society we expect people to provide the level of care that Ms Burrows was providing for that hourly rate.
"For each of those half-hour visits she made she was required to perform tasks that I suspect a lot of people would find very difficult."
But he added it was irrelevant to the offence committed as it was a job she had agreed to do, and the standard of care required of her was not any less because her pay might be regarded as poor.
Following sentencing, Detective Inspector Craig Turner, of Merseyside Police, said: "Tracey was in a position of care and has abused this trust, ultimately resulting in the sad passing of Ms Cleworth.
"Although this is a really awful series of events, I hope this sentencing brings some closure to Ms Cleworth's family and allows them to move on with their own lives."