The E4 teen drama's last run will be comprised of three stories - each divided into two one-hour episodes - titled 'Skins Pure', 'Skins Rise' and 'Skins Fire'.
'Skins Pure' - written by series co-creator Bryan Elsley - will see Murray reprise her role of Cassie, who will be seen "adrift, alone and invisible in London", ultimately forming a poignant friendship with a mysterious stranger.
'Skins Rise' - by Jamie Brittain - will focus on the character of Cook (O'Connell), as the tearaway is forced to confront his own violent past while working as a drug peddler in Manchester.
"I am delighted that three emblematic actors, currently embarking on successful movie careers, are returning to E4 and Skins," said Bryan Elsley.
"They will play their iconic characters as they emerge into adulthood, and bring new challenging stories of young adults, grappling with life in Cameron's Britain, to vivid and entertaining focus."
Sophie Gardiner, commissioning editor of Channel 4 Drama, added: "Always innovative, always truthful, Skins is a show that defined a generation. That generation is growing up. Skins seven catches up with our characters as they continue in their path to adulthood, finding out who they are going to be, and who their friends really are."
The final series of Skins will shoot in Manchester and London from October to January to transmit in spring 2013 on E4.