The girl band, which formed on 2002 reality TV show Popstars: The Rivals, took a break in 2009 to allow the stars to concentrate on individual projects, but announced last October they were ending the hiatus.
The five-piece - Cole, Sarah Harding, Nadine Coyle, Kimberley Walsh and Nicola Roberts - released a new single and greatest hits album, and on Thursday they launched their Ten Tour at the Metro Radio arena in Newcastle, north-east England.
The pop stars were lowered from the roof of the venue under a huge Girls Aloud sign, and launched into a hits-packet set, including their debut single Sound Of The Underground, The Promise and Something Kinda Ooooh.
Cole also used the concert to show off a new tattoo after having two large roses inked on her back.
The singer, who hails from the city of Newcastle, took to her Twitter.com page after the gig to declare: "I wish I could find the words to express how I feel right now!! Newcastle was perfect", while her bandmate Kimberley Walsh added, "Unbelievable first show tonight. Thank you Newcastle!!!"