A judge told Kamal Bains that his failure to fit smoke alarms in the house in Huddersfield was a “significant cause” of the deaths of Logan Taylor, three, and two-year-old Jake Casey, two.
The youngsters died when an electrical fault in a TV caused a fire in their bedroom in February 2016.
Their distraught mother, Emma Taylor, told Leeds Crown Court that she was beaten back by the heat and smoke as she tried to rescue them.
Bains, 51, of Stableford Gardens, Huddersfield, whose property company managed the house, admitted a breach of health safety law on Monday.
He had been on trial for manslaughter in a prosecution thought to be the first of its kind.
But the manslaughter charges were dropped after he admitted the health and safety violations.
He was jailed on Wednesday by Mr Justice Males, who told him: “Your failure to fit smoke alarms was a significant cause of the children’s deaths.
“Thus the harm caused by your failure could not have been more serious.”
Bains was the director of property management company Prime Property Estates (Yorkshire), which maintained around 140 homes in the Huddersfield area on behalf of private landlords for a 10% cut of the rent.
Ms Taylor told the two-week trial, which ended when the manslaughter charges were dropped, that she asked Bains “time after time” to fit alarms at the house he managed in Alder Street.
In an impact statement read to the court, she said: “I don’t think I will ever recover from this awful tragedy. The worst thing is I won’t get to see my boys grow up.”
The judge said that tests carried out by investigators showed that Ms Taylor would have had “a few minutes” to rescue her two boys if an alarm had been fitted.
He said it had become obvious during the trial that the prosecution “could not sustain” its manslaughter case.
He told the court: “I want to conclude by making it absolutely clear that, whatever some people might think, the sentence which I am passing today is not in any way a reflection of the value of the lives which have been lost.
“The lives of Logan and Jake were of infinite value and nobody must be in under any misapprehension about that.”
Ms Taylor and Mr Casey, the boys’ father, said in statement after the hearing: “We do hope that this case highlights this important issue and for people to know their responsibilities as landlords or letting agents and to take appropriate action to ensure that any property they are responsible for has working smoke alarms.
“Such a simple check could have saved the lives of our boys and we want to ensure that this does not happen to anyone else.”
West Yorkshire Police said this is thought to be the first prosecution of its kind in the UK since new legislation was introduced in October 2015 which said that private sector landlords are required to have at least one smoke alarm installed on every storey of their properties.
Detective Superintendent Steve Thomas said: “We also hope that this case is a stark reminder to landlords and letting agents to treat their responsibilities seriously and they have an obligation to ensure that all properties are fully equipped with all adequate safety measures to ensure the safety of their tenants.”
West Yorkshire’s Deputy Chief Fire Officer, Dave Walton, said: “Had there been working smoke alarms in this property, the outcome could have been very different and these brothers could have had a future to look forward to.
“As firefighters, the importance of having working smoke alarms is a message that we try and get over to the public day in and day out.”
He added: “This landmark case shows how vitally important it is that landlords and letting agents take their responsibilities seriously or the consequences do not bear thinking about.”