The sentence included a non-parole period of of eight months.
In the Downing Centre Local Court today, Chief Magistrate Graeme Henson ordered the sentence be served in protective custody.
Power's double life - as a respected senior counsel, and a senior prosecutor with the NSW Office of the Director of Public Prosecutions - came undone when a technician, called in to fix Power's computer, discovered the cache of images in July last year.
Investigators unearthed 29,000 images on the computer hard drive, most of them homosexual porn, with 400 pornographic still images featuring children as young as five.
There were 31 videos featuring adults engaged in sex acts with children, catalogued in a folder named "good".
Power, 54, pleaded guilty to possessing child pornography and resigned from the office of the DPP this year.
At a previous court appearance in late April, the court heard that Power had refused a police request to give them a missing hard drive containing more pornographic images.Mr Henson said Power - who holds a master of laws and a doctorate - was a highly intelligent man and there would have been few people better placed to have known the gravity of his actions.
The Chief Magistrate today accepted a proposition from Crown Prosecutor Jeremy Rapke, QC, that Power had been functioning as one of the state's most senior prosecutors while being treated for depression and committing a criminal offence.
The Crown had argued that there had not been the slightest suggestion that Power had been incapable of his professional duties at the time. It also queried how it could be that his judgement had been impaired in one sphere only.
Shortly before Power was led away to the cells, the NSW Bar Association made an application to the court to have News Limited charged with contempt over its recent coverage of the case.
The application will be dealt with at later date.
Power's sentence has renewed calls for an independent judicial inquiry into cases dealt with by Power during his career with the DPP.
Supporters of Roseanne Catt - who spent 10 years in jail for conspiracy to murder her husband, before her conviction was overturned by the Court of Criminal Appeal after it found evidence against her might have been fabricated by serving police officers - gathered outside Downing Centre Local court today.
"All of Power's cases involving the prosecution of pedophilia whistleblowers need to be investigated transparently and independently of the DPP," they said in a statement.
"Roseanne Catt's case should be at the top of the review list where the sexual abuse of children was at the heart of her matter."