Hundreds of screaming teenagers queued in the city centre to catch a glimpse of the Aussie group.
They were in Glasgow yesterday to sign copies of their chart-bursting single, She Looks So Perfect.
And hundreds of adoring fans flocked to HMV, on Buchanan Street, to see their idols.
The queue snaked from Buchanan Street and into Sauchiehall Street as fans waited for hours to see their pop rock idols.
As well as signing copies of the new single, band members spoke to fans and posed for photographs.
The band - Michael Clifford, Luke Hemmings, Calum Hood and Ashton Irwin - have been together since 2011.
Last month, 5 Seconds of Summer - also known as 5SOS - kicked-off their UK tour at the O2 ABC in Glasgow.
The band previously toured with One Direction and have notched up millions of hits online.
Their debut UK single, She Looks So Perfect, rocketed to No1 in the UK iTunes chart and 48 other countries.
The band shot to fame after posting videos of themselves performing covers of popular songs together on YouTube including a cover of Chris Brown and Justin Bieber's "Next to You".