Former Bond girl Fullerton claimed that Reid lacked charm and had expected to win the competition in her column for The Telegraph.
Fullerton - who was the seventh celebrity to be voted out this year - explained that she felt Reid had alienated other contestants with her "PR campaign".
She wrote: "All those votes from Grimsby couldn't save Susanna Reid, who approached this competition with a PR campaign driven with military precision.
"There was definitely an Obama-style use of social media and a lack of charm that left most of us bewildered.
"Every time she entered Tess [Daly]'s room there were uncomfortable mutterings. It seemed she'd convinced the media she was the outright winner."
However, Fullerton was more supportive of Reid's fellow finalists. Speaking about fourth-placed Sophie Ellis-Bextor, she said: "We