user: Text: Media playback is not supported on this device
The world number 10 from Antrim made the clearance against Englishman Rod Lawler.
It put Allen 4-3 ahead, and the 30-year-old went on to secure a 6-4 victory.
"It was a big buzz as I'd never made one on tour. I'm very happy and it was relief when the black went in - I was nervous and I was shaking," he said.
The maximum is worth £5,000 from the rolling prize pot for 147s at ranking events, plus a £5,000 high-break prize if it is not matched.
Allen will take on Ryan Day or Kurt Maflin in the last 16 at the Barbican.
A beaten finalist at the Barbican five years ago, Allen came close to a 147 in 2010 at the World Championship, potting 15 reds and 15 blacks before missing the green.
He then went on to make a 146 in the same competition.
However, he made no mistake against Lawler and had been eyeing up the possibility after potting just six balls.
He added: "The balls were sitting so nice from 24 and I was thinking about it from then. The reds were all sitting, none on the cushions, and you can only mess it up from there.
"I went to the toilet afterwards to calm myself down and take deep breaths, control the breathing and take the shakes away."
summary: Northern Ireland's Mark Allen hit his first career maximum 147 break at the UK Championship in York on Sunday.
Text: Three years after rowing to the North Pole, he will trek there with 14 rugby players.
Their aim is to play the most northerly game of rugby sevens in the sport's history in temperatures that could reach -50C.
As well as being physically and mentally ready, he said players needed to respect the hostile environment.
"We would rather they be scared than be over-confident," he said.
"Because once you are scared then you listen and once you listen then you achieve.
"I don't see major problems in the physical side, it will probably be in the mind and how they take in what we call 'polar shock'."
He said everyone suffered from the extreme cold, especially in their first days.
"It is usually in the first week that they make the mistakes - and a mistake up there very easily can go very badly wrong," he added.
Andrew Walker, from Closeburn, is one of four Scottish players taking part in the challenge which aims to raise Â£300,000 for Wooden Spoon, rugby's charity for children.
"Jock has mentioned previously that you can't really prepare yourself mentally so I will just need to hope I hold up for that," he said.
"Physically I feel good, about three weeks ago I really thought I turned a corner and feel good-to-go.
"I feel fit, strong and I'm only 27 at the end of the day - Jock's got about 40 years on me, so if he can do it I can do it."
summary: Dumfries-born polar adventurer Jock Wishart is about to embark on his latest challenge.
Text: Amanda Mellet was told her baby would die in her womb or shortly after birth.
She was 21 weeks pregnant in November 2011 when doctors gave her the news.
The law in the Republic of Ireland meant that Ms Mellet was not able to access an abortion in the country.
She travelled to the UK for an abortion, but had to return home 12 hours after the procedure as she couldn't afford to stay away from home for longer.
The UN criticised the Irish government for putting Ms Mellet through financial and emotional suffering.
In the report, it said she had to choose "between continuing her non-viable pregnancy or travelling to another country while carrying a dying foetus, at personal expense and separated from the support of her family, and to return while not fully recovered".
The UN said the Irish government should compensate Ms Mellet and ensure she gets proper psychological treatment.
It has also instructed the Irish government to ensure similar violations don't happen again.
The UN's Human Rights Committee called for the strict prohibition on abortion in Irish law to be reversed to allow women who are told their baby has a life-limiting condition to be able to terminate the pregnancy safely.
summary:

assistant: The United Nations (UN) has found strict abortion laws in the Republic of Ireland's subjected a woman to discrimination and cruel and inhuman treatment.