Some fans queued for more than four hours to meet The X Factor runner-up and Xtra Factor host.
The 28-year-old signed copies of his autobiography, Happy Days, for more than 400 lucky fans, at the city's St Enoch Centre.
Die-hard fan Skye Dione Clark, 12, was in tears after getting her copy of the Essex singer's book signed.
Olly said: "My life has been a non-stop roller-coaster of extreme emotions, crazy days, unexpected highs and yet my life hasn't been without its low points too."
Hundreds of Olly's fans had braved the October chill, some from 7am, on Saturday to queue up and collect a wristband from WH Smith, in Argyle Street. Among those who had queued were friends Sophie Bateman and Abbie McIntosh, from Cumbernauld.
Sophie, 16, said: "We queued from 5am on Saturday to get a wristband and today just made it all worth while.
"He was so lovely. I'm so glad I got the chance to meet Olly."
Abbie, also 16, added: "We love Olly so much, we just had to come down and see him."
Olly is set to appear at the SECC on Friday March 15.