Gavin Coyle, 36 and from the Culmore Park in the Co Tyrone town, was initially arrested in April 2011 over the weapons, explosives and ammunition found in a lock-up garage in Coalisland.
The discovery was made three days after Constable Kerr's death, caused by an under-car bomb which exploded as he prepared to drive to work.
It's believed the 25-year-old Catholic officer was targeted by republicans in an attempt to scare others with a nationalist background from joining the PSNI.
Items recovered from the building at Mountjoy Road included Semtex plastic explosive, rocket propellant, detonators, improvised timers and power units, homemade grenade initiators, a quantity of improvised incendiary devices, four AK assault rifles, six loaded magazines and a quantity of ammunition.
Coyle, who admitted membership of an organisation calling itself the 'New IRA', was linked to the arms find by DNA evidence and by explosives residue on his clothes.
On Wednesday, he was handed a 10-year jail term - half of which will be served on licence.
You have been involved in serious terrorist-type activity, you have admitted to membership of what you describe as the 'new IRA'.
Coyle was given a six-year sentence for IRA membership, 10 years for possession of explosives and 10 for possession of firearms, with Judge Philpott ordering that the terms be served concurrently.
After hearing pleas from defence and prosecution lawyers, the judge said she had taken into account Coyle's admission of guilt in mitigation.
"He has now shown remorse by pleading guilty," she said.
Judge Philpott said she had given extra credit for the guilty plea as there were elements of the case that could have been contested during a trial.
She said she had also factored in that the charges related to "keeping or assisting in keeping" the weapons for others, and not for deployment by himself.
But she said an aggravating factor was the nature of the weapons haul that had been found.
Judge Philpott said the ammunition, explosives, mortars and grenades that were a "serious find".
"It's very fortunate that police discovered these items before they could be put to use," she commented.
"Regarding the firearms, the AK47s are of some considerable vintage. It looks on the face of it that these weapons have been re-activated."
Coyle has already served around two years and eight months in custody.
After his licence expires, he will still have to notify police of his whereabouts for a further 10 years.
While a number of arrests have been made in connection with Constable Kerr's murder itself, no one has yet been convicted.
We have made progress and we believe there is potential to bring other individuals before the courts.
ACC Drew Harris
Since the police investigation into the series of linked incidents began on 2 April 2011, 7,947 items have been seized; 13,936 individuals have featured in the investigation; 123 searches of houses, vehicles and land have been conducted and 14 arrests have been made.
The senior PSNI officer in charge combating dissident republican terrorists said Coyle's sentencing was "a significant milestone".
"The Mountjoy Road arms find is one of the biggest in recent years. On one very important level, it has saved lives and significantly disrupted a terrorist group,"
Assistant Chief Constable Drew Harris said.
"On another, more strategic, level, it forms part of the police investigation into a series of linked incidents which include Constable Kerr's murder in Omagh on 2 April 2011.
"Although we have yet to bring charges for Ronan's murder, this investigation, which is the largest in the PSNI's history, is far from over."
ACC Harris continued: "Detectives in Serious Crime Branch have linked a total of 17 incidents to the same network of individuals and terrorist groupings. These include attempts to murder other police officers, a bomb attack, arms finds and armed robberies.
"But we are not complacent. We recognise the considerable challenges remaining in this lengthy and complicated investigation."