Cameron Watson was recorded by a police officer taking two roundabouts at speed before he was pulled over, Teesside Crown Court heard.
The 26-year-old Northumbria Police officer was arrested by police as he drove along the A688 in Spennymoor in the early hours of the morning after he undertook their car at speed.
Lewis Kerr, prosecuting, said the incident was captured entirely on camera and the police car was an unmarked vehicle.
He said: “He was driving at high speed and too close to the rear of the vehicle, it’s clear from the footage that the vehicle is undertaken by him and drives on.
“As soon as the lights and sirens were activated, he pulled over at a safe spot after he reached speeds of nearly 120mph.”
Judge Jonathan Carroll watched the two-minute video before sentencing Watson.
He said: “A very significant feature of this case is that you are a serving police officer. You had been on duty that night and the end of your shift resulted in you being some considerable distance from home and you decided that you just wanted to get home quickly.
“I suspect that there is not a single person in the world of work that has not had the occasion when they wish they could just get home quickly.
“Very few people with that kind of need end up driving at just shy of 120mph. The reason why they don’t is because, even without police training, they know that is a truly dangerous and reckless thing to do.
“Had you lost control of your vehicle, you would have almost certainly killed yourself or endured life-changing injuries.
“You are not just risking your life; you are risking the life of any other road user.”
He added: “There is an air of entitlement of that behaviour, some sense that ‘I am a police officer, I am allowed to do so because I am special’ that is certainly the tone of what you said to the arresting officer.”
Watson, formerly of Newton Aycliffe but now of Ennerdale Terrace, Low Westwood, Newcastle, pleaded guilty to dangerous driving on August 26 last year.
Elisha Marsay, mitigating, said her client had pleaded guilty at the earliest possible opportunity.
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She said: “One mistake should not determine the trajectory of a 26-year-old man’s life. He made a significant mistake that evening and the gravity of that mistake is lost on him.
“It is one-minute 44 seconds of sheer stupidity.”
The was sentenced to a community order and told to carry out 300 hours of unpaid work and banned from driving for 12 months.
The officer will now face a police disciplinary hearing as a result of his criminal conviction.