Neil Weiner launched the "wickedly evil and vile plot" hoping to get Eddie Thompson sacked so that he could be promoted.
Weiner, 40, was convicted of perverting the course of justice and two counts of possessing indecent images of children at the Old Bailey.
Judge David Paget told him: "What you did to a decent and honest man was in my view wicked.
"It is difficult to imagine a more cunning, deceitful or warped course of conduct than yours in this case, or a more malicious one."
The court heard how he sent police a CD containing indecent images of children saying they came from Mr Thompson's laptop.
Hundreds more pictures were later found on the computer and the caretaker was arrested in October 2006.
He told police he had been set up by colleagues who did not like him but it was eight months before he was told no further action would be taken.
When the details of the allegations were leaked by Weiner to a local newspaper, Mr Thompson and his wife became afraid to leave the house, after he received threats and they were spat at in public.
Even when he returned from suspension to Swanlea secondary school, in Whitechapel, east London, where he had worked since 1993, Mr Thompson said he was shunned by nearly all the staff, making his life "almost unbearable".
"My life and good name was nearly destroyed by a villain who tried to destroy my reputation in a monstrous manner," said the Scottish-born caretaker, 62, in a victim impact statement read to the court.
"This must be the work of a depraved mind."
Jurors heard that Weiner, a computer "wizard" who worked at the school as a handyman assistant, was arrested in 2007 after a mobile phone used to make an initial anonymous call to police about Mr Thompson was traced to him.
Richard Milne, prosecuting, said the child pornography on the caretaker's computer was planted by Weiner "for no better reason than to get him the sack so that he could get promotion, and because he did not like him".
Some of the images were level 4, the second most serious.
"He was being fitted up or framed on his computer," said Mr Milne.
The prosecutor told jurors that others who found out about it were "horrified by what you may think was a wickedly evil and vile plot".
Weiner, a married father of two from Dagenham, east London, was convicted in August of the three charges he faced, each by a 10-2 majority.
Today he was given a 12-year sentence for perverting the course of justice plus a total of five years for the two child pornography charges, to run concurrently.
The judge told Weiner that his plot to have Mr Thompson sacked and prosecuted very nearly succeeded.
Police had been careful not to make public their arrest of the caretaker and only informed those at the school who needed to know, he said.
"But you gratuitously and spitefully informed the local press so that he and his wife suffered the distress of the unwelcome publicity which followed."
Mr Thompson's health and that of his wife suffered.
The judge said: "There are still those who believe, and probably always will, that he is a paedophile. I am wholly satisfied that Mr Thompson is innocent.
"Your reason for trying to ruin Mr Thompson in this way must have been simply that you didn't like him. You must have hated him with a vengeance."
Weiner had discovered the caretaker's password by looking over his shoulder one day and been caught doing so.
When Mr Thompson was asked why he did not change it, he said he wished he had, adding: "Who in their worst nightmares would could have thought that anyone could stoop to do what he did?"
The judge said there was no evidence that Weiner was a paedophile but his conviction for possession of the images meant that he had to be placed on the sex offenders register.
He told him: "You will go to prison for a long time. The prison population is not renowned for being particularly fair or reasonable.
"You will be suspected by many of being a paedophile and, like Mr Thompson, you may find that you suffer, both in prison and on release, for the rest of your life.
"All these consequences will last for life and the irony is that you have brought them upon yourself by your own deliberate conduct."
The judge had previously said that Weiner's crime was "as serious an offence of its kind as I personally have ever come across".
Mr Thompson, who was in court to see Weiner sentenced, admitted to the jury during the trial that he had a reputation for being "exceedingly grumpy, bad-tempered and irascible".
But he said he had the "fright of his life" when police told him what had been found on his computer.
In his victim impact statement, he said: "My good name was besmirched. I have been recognised many times whilst walking in the street, to the embarrassment and emotional hurt of my wife and myself.
"We were most offended by the disgusting act of being spat at in the street on several occasions.
"Even to the present day, on occasion I still have to suffer the scorn and disdain of members of the local community and there remains an element of apprehension in working in the area."
He added: "Now that the truth has come out, perhaps my wife and I can have closure on this dreadful episode of our life."
