This week, all 700 pupils at John Paul Secondary, Summerston, turned up to classes in smart black blazers.
They were designed by pupils and has the school motto, In Knowledge May Goodness Abound.
Vincent Docherty became head teacher three years ago and found pupils turning up to class wearing "sloppy" street clothes and trainers.
He introduced a partial uniform of black trousers and shoes, a blue shirt and yellow and blue tie.
Two years ago, sixth year pupils were asked to wear black blazers and fifth year followed in 2011.
Mr Docherty had planned to phase in the introduction of blazers across the rest of the school, but was stunned when younger pupils asked if they could also wear blazers.
He said: "The huge surprise was parents wanting all the pupils to be wearing blazers and the children asking for them.
"It is astonishing because we would never have predicted that.
"Today is a historic day because every pupil has turned up in a blazer and they look fantastic.
"It is incredible because there has been 100% commitment to the school."
When Mr Docherty took over as head teacher, John Paul's had one of the highest exclusion rates in the country.
For the past three years, it has had the lowest exclusion rate in the city and attainment has approved dramatically.
Mr Docherty said: "Over the past few years we have seen things improve.
"There has been a dramatic change in attainment and the prediction for sixth year attainment this year is the highest the school has had in its history.
"I am very proud and John Paul Secondary is a fantastic place to work."
Girls at the school designed a fitted blazer, while boys opted for a blazer more like a suit jacket.
Mr Docherty said: "I think they all feel grown up wearing them, are proud to be part of the school and are taking their education really seriously.
"We talk about young people misbehaving and the difficulties they get into, but this really is proof of the commitment the pupils are making to the school.
"Wearing uniform has greatly enhanced the youngsters' behaviour and learning."
An added benefit of school uniform is that pupils are no longer bullied for not wearing the most expensive trainers or street clothes.
And security is improved because staff can immediately spot a young person who should not be in the school grounds.
The blazers cost £40, although the secondary subsidises each one, charging parents only £30. However, help is given to any parent who cannot afford the money to buy a blazer.
Stephen Curran, the city council's executive spokesman for education, said: "These are significant improvements.
"It is wonderful to hear how well the head teacher, his staff, pupils and parents are working together for the benefit of the school and its pupils.
"It is really refreshing that all the youngsters want to wear a blazer and even more so to be proud to wear it. They are exemplar ambassadors for their school and Glasgow."