The celebrity tailor and fashion designer said at the college’s annual awards evening: “I was a bit of a troublemaker before I came here.
“I could easily have gone down a criminal path. I had no direction.
“It really did turn my life around. I’m very thankful for my time here.”
He said that he was opening a new shop in Shoreditch, East London, next week.
Mr Blake was presented with a “Golden Alumni” award by City College principal Phil Frier and the Lord Lieutenant of East Sussex Peter Field.
The same pair presented 40 awards to City College students, celebrating a range of achievements and triumphs over adversity.
The college’s City Achiever of the Year award went to catering and hospitality student Asha Phelps, 17, from Elmore Road, Brighton.
She cried with joy on receiving the award and there were a few tears in the audience too.
Her tutors paid tribute to her hard work and dedication even though she sometimes had to help care for her mother and her younger brother and sister.
Afterwards her mother Kim shed tears too, telling her daughter she was so proud.
Kim suffers from poor health and sometimes needs care. At other times she has been in hospital and Asha has had to look after her 13-year-old sister and four-year-old brother.
The former Falmer High School pupil said that she was surprised and delighted to have won the top award.
She said that she came to City College hoping to be a chef but the course had opened her eyes to the many possibilities in the catering and hospitality sector.
She said: “You see how big the industry is and all the opportunities.
“I had experience in the kitchen before my course but not front of house. We had to learn how to waitress to a five star standard, we had to learn silver service, how to pour wine elegantly.”
After completing Level 1 catering and hospitality last year, Asha is now developing her skills on the Level 2 course.
Mr Frier told students and their families at the start of the evening: “There are only 40 achievers here out of 10,000 students.”
He said that the 40 had been chosen because of their achievements.
He said: “I hope you like your gowns. You look really good in them.
“When I first started teaching at a sixth form in Haywards Heath 35 years ago we had to wear gowns.
“The latest teaching technology was chalk – and blackboards.
“And the good thing about these gowns was that you could wipe the blackboard clean with them.
“In the lift this evening I heard someone say, ‘You look like a Jedi!’
“Well, I want you to think of yourselves as Jedi masters.
“You were part of the best Ofsted result this college has ever had – and the best exam results.
“It’s not just about qualifications. It’s about jobs. That’s the next step for most of you.
“About 85 per cent of our students go on to jobs in this city.”
He said that some went on to higher education too, adding: “We are the engine room of this city and that makes me very proud.”
Among those collecting awards was Brighton and Hove News contributor Claire Smyth who completed a journalism course at City College in the summer and boxing champion Archie Hutchins.