The 29-year-old was shot in the head when a masked gunman fired towards police during a riot in Derry/Londonderry in April 2019.
Judge Mrs Justice Smyth delivered her judgment in the long-running non-jury trial at Belfast Crown Court.
Prosecutors said Paul McIntyre, 58, Peter Cavanagh, 38, and Jordan Devine, 25, all from Derry/Londonderry, assisted and/or encouraged the gunman.
They had denied the charges.
The defence criticised the standard of evidence in the case, saying it was almost entirely circumstantial.
The self-styled New IRA admitted responsibility a few days after the murder, and said she was "tragically killed while standing beside enemy forces".
Several petrol bombs had been directed at police and a car was set on fire during chaotic scenes which culminated in four shots being fired towards officers. One of the shots hit Ms McKee.
Police later recovered the handgun that killed Ms McKee and believe it was also used in prior attacks.
As a rising star in journalism, Ms McKee extensively covered the Northern Irish conflict and its legacy, and was named Sky News young journalist of the year in 2006.
Speaking outside the court, Ms McKee's family said she deserves "justice".
Her sister, Nichola Corner, said: "I'll tell you what will not happen, that we will not go down with this. This is not over. Lyra said, 'If you're going to go down, go down fighting'.
"And I can tell you right now that every one of my family will, because we do this for Lyra."
Originally from Belfast, Ms McKee had only recently moved to Derry/Londonderry before she was killed, to live with her partner Sara Canning.
She had tweeted about the "absolute madness" in the city in the hours before she was shot dead.
A television crew had been filming in the area with the republican organisation Saoradh for a documentary for MTV.
After filming around several locations in the morning, they left before the shooting happened.
During the trial, the court was shown unedited footage from the documentary filmed in the Creggan estate on the day of Ms McKee's murder.
The murder sparked an outpouring of condemnation and grief which quickly spread beyond Northern Ireland and went around the world.
Former Irish president Michael D Higgins, then prime minister Theresa May, and former Taoiseach Leo Varadkar were among the mourners who attended her funeral.
Anastasiia Berezovska, a 39-year-old from Ukraine who has a tattoo, possibly of a snake, on her right arm from the shoulder to the elbow, has been named as the suspect in a red notice - a call for her to be arrested wherever she is.
Berezovska has since been spotted in Germany, a source told the Reuters news agency.
A Monaco prosecutor said she was disguised as a man.
The parcel bomb blast in the wealthy principality was believed to be an attack on a Ukrainian-born oligarch.
He was named in local news outlets as Vadym Iermolaiev, with Ukrainian media claiming he has previously been targeted with sanctions because of his ties to Russia.
Speaking on Friday, the Monaco prosecutor outlined fresh details about the case - including about the device used in the attack.
A remote control was used to detonate the bomb, they said, and due to its complexity, police are investigating possible accomplices and those who may have ordered the attack.
A car with a German licence plate, which went through Italy and some other countries, was likely to have been used by the suspect, the prosecutor said.
Police opened an attempted murder investigation at the time but did not qualify it as a terrorism investigation, prosecutor Stephane Thibault said.
Three people were injured, including a woman who was in a life-threatening condition, he said earlier this week.
The other two are a man, who was no longer in a life-threatening condition, and a child, whose life was not in danger, he added.
The search for the suspect is continuing, and authorities have launched an arrest warrant.
Iran International journalist Pouria Zeraati was stabbed three times in the leg in an attack outside his home in Wimbledon, south London, on 29 March 2024.
Romanian nationals Nandito Badea, 21, and George Stana, 25, were sentenced on Friday after being found guilty of wounding with intent to cause grievous bodily harm at Woolwich Crown Court in June.
Badea was given an eight-year jail term, and Stana was sentenced to 12 years.
The men were members of a team that flew in from Romania and spent a month surveilling Mr Zeraati's block of flats on Queensmere Road.
The target of the plot, Mr Zeraati, was a high-profile presenter for Iran International, a dissident TV station based in Chiswick, west London, until February 2023.
Threats made against the network, its employees and their families led to it relocating temporarily to Washington DC.
Mr Zeraati had appeared, along with other journalists, on "Wanted: dead or alive" posters that were put up in the Iranian capital Tehran.
Police said the pair fled the UK within hours of the attack, flying from Heathrow to Geneva after travelling there by taxi.
They were arrested in Romania in December 2024 and extradited to Britain later that month.
Prosecutor Duncan Atkinson KC told the court that Badea and Stana were motivated by money but were acting as criminal "proxies" for the Iranian government.
The judge added that the "foreign power condition" under the National Security Act applied to Stana, increasing his sentence because he knew, or should have known, of the link to Iran.
Following the sentencing, Chief Superintendent Kris Wright, head of Protective Security Operations for Counter Terrorism Policing London, said the attack was "targeted" and "carried out on behalf of the Iranian regime".
Read more from Sky News:
Three men found not guilty of murdering journalist Lyra McKee
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He went on: "Both men are facing a considerable time behind bars for their actions, and Stana having his sentence extended because he knew or ought to have known this attack was on behalf of Iran.
"Our recent casework shows an increasing use of so-called 'proxies' by hostile foreign states to conduct illegal activity and attacks in the UK.
"But this case, and others, show that we will not tolerate this and that we will work with our partners in the UK and internationally to identify those involved and bring them to justice.
"Our message to anyone being asked to carry out activity by foreign states or even unknown entities online is to think again, because you will be caught and you will face justice."
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Yellow heat health alerts have been issued for multiple regions across England, warning that health and social care services are likely to be affected.
The alerts - issued by the UK Health Security Agency (UKHSA) - cover East Midlands, West Midlands, London, the east, southeast and southwest of the country from 12pm this Saturday until 8pm on Saturday 11 July.
See the weather forecast for your area
The UKHSA said the high temperatures will likely lead to an increased use of healthcare services by vulnerable people and poses a "greater risk to life" for that group.
The agency is also warning of a potential rise in water-related incidents, including risks from cold water shock and drowning.
It comes after a record-breaking heatwave last week, which led to rare red alerts from the Met Office.
Sky News weather producer Kirsty McCabe said: "I think the key difference between this hot spell of weather and last week will be the humidity level.
"While things are getting hotter and we're likely to meet the heatwave criteria - three days in a row above the heatwave threshold temperature - this hot spell won't be as unbearable.
"And it won't be as widespread either, with cooler, cloudier and wetter conditions for northern parts of the UK - mainly for Scotland that won't see an improvement until the middle of next week."
She added: "Last month we were under a heat dome, a persistent area of high pressure that was over much of Europe, with very hot air dragged up from North Africa.
"This time round we have high pressure that has extended from the Azores and westerly winds, so temperatures won't be as extreme.
"And although the humidity will creep up, it won't reach those oppressive levels so the nights won't be as uncomfortable for sleeping.
"So, we're looking at more typical summer weather and maximum temperatures close to or just above 30C."
At least seven people died in water-related incidents during last month's heatwave, following on from 15 in May.
Ms McCabe said the UKHSA alerts are aimed at healthcare professionals - not members of the public - but are useful to "get a heads up", especially for those who struggle with hot weather.
She added: "At the moment there are yellow-level heat health alerts for south and eastern parts of England. Last month there were widespread amber-level heat alerts.
"More significantly, the UK Met Office issued red and amber extreme heat warnings, and this was only the second time a red extreme heat warning had been issued.
"The first time there was a red extreme heat warning in place for three consecutive days. To be fair, extreme heat warnings have only been around since 2021."
The UK set a provisional June temperature record of 37.7C last Friday in Lingwood in Norfolk, the Met Office said, topping the previous UK June record of 35.6C from 1976 by more than 2C.
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In response to the recent hot weather, a hosepipe ban is to be implemented across Hampshire and the Isle of Wight from 10 July.
Southern Water said the restriction is being put in place after the warmest spring on record for England and Wales, and the subsequent record-breaking heatwave, left river levels 25% lower than expected for this time of year.
The firm said the River Test had lost a third of its water within the last month.
Southern Water said: "We'll remove the hosepipe ban as soon as we can, but this can only happen when there's enough water in our reservoirs, rivers and underground aquifers to meet demand."
Meanwhile, millions of Americans are facing dangerous heat and humidity going into the Fourth of July holiday.
As the US celebrates the 250th anniversary of American independence from Britain, cities such as Chicago, Detroit, New York and Boston have hit 100F (37.8C) in recent days.
The National Weather Service has warned that the extreme heat will continue across much of central and eastern US throughout Friday and along the east coast through the weekend.
Kian Bateman, 19, was found guilty of murdering Shelley Davies, 38, and causing her partner, David Bratcher, grievous bodily harm, following a trial at Cardiff Crown Court.
Bateman had been taking nitrous oxide before he drove his mother's Seat Ibiza at the couple outside the 4th Glamorgan Home Guard Club in the city, the court heard.
On the night of the murder last September, Bateman, then aged 18, had been visiting the social club to attend a General Levy gig with friends.
Bateman left the venue in the car to visit his girlfriend after the bar closed.
However, after realising she had not yet returned home from work, he drove back to the venue where people had gathered outside and the atmosphere was growing "ugly".
The court heard Bateman saw his brother in a row with a group of people, during which Shelley Davies ended up on the ground.
Bateman then deliberately drove his car at the group, running over Ms Davies.
He also hit her partner, David Bratcher, then aged 40, leaving him seriously injured.
Ms Davies, 38, later died in hospital on 18 October due to her injuries.
Mrs Justice Stacey, who on Friday sentenced Bateman to life imprisonment with a minimum term of 17 years, said he "drove straight over (Ms Davies) at about 10mph".
"You did not stop, but drove off... You handed yourself in the next day."
"I am satisfied and I am sure that you did not see Ms Davies lying in the road in front of Mr Bratcher and I accept that you did not intend to cause her any harm.
"But because she was in the way when you were trying to cause really serious harm to Mr Bratcher, it means that you are guilty of Ms Davies' murder."
Bateman, of Cardiff, admitted causing death and injury by dangerous driving and was convicted by a jury of murder and causing GBH with intent.
Read more from Sky News:
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Ms Davies was described in court by family as a "force of nature" who worked as a Reiki healer for those struggling with addiction.
In a statement read to the court, Mr Bratcher said: "She was the person I loved, my best friend, and the mother of our three children.
"Losing her in such a sudden and violent way has changed our lives forever."
The court heard Bateman has a learning disability, has shown remorse for the murder and has no previous convictions.
In addition to his prison sentence, Bateman was disqualified from driving for 21 years and 109 days and ordered to take an extended re-test.