The 17-year-old was the early bookmakers' favourite to win the competition, and when the details of the public vote winners and runners-up were revealed on tonight's Xtra Factor, Devlin's popularity was confirmed.
Devlin won the week two vote, ahead of boyband The Risk. She also triumphed in week three, ahead of Louis Walsh's act Johnny Robinson.
Janet also won the fourth and fifth week votes ahead of Little Mix and Marcus Collins respectively.
Amelia Lily's return in week six earned her the top spot, ahead of Devlin, while week seven featured Little Mix at the top for the first time. Misha B claimed the runner-up spot in week seven. Amelia Lily returned to the top in week eight, ahead of Little Mix.
The Middlesbrough teenager, who was voted back in the competition as a replacement for Frankie Cocozza, then slipped down the votes in the semi-final beneath Little Mix and Marcus.
Little Mix were crowned the X Factor champions on tonight's final (December 11). The group's winner's single 'Cannonball' is available to buy on iTunes now.