The 23-year-old will compete against presenter Laura Hamilton and actor Sam Attwater to win the sixth series of the ITV1 show. All three have topped the judges' leaderboard at some stage during the series.
"Chloe has been a little battler. She has really fought very strongly to remain in the competition," Gardiner wrote in the The Sun. "Although she lacks the presentation skills and panache of others, her innocence and the fact she gives her best means she deserved her place in the final. She is the outsider but is unpredictable. Don't write her off."
The judge had previously been critical of early favourite Attwater, claiming that the ex-EastEnders star should "worry" about inconsistencies in his routines which are putting his position as "frontrunner" in doubt.
"He was back on form on Sunday," he said. "Sam really came back into his stride and his partnership gelled brilliantly. He gave what I considered to be a true semi-final performance in both his solo and partnered routine with Brianne. I am absolutely thrilled that he is a finalist. I always hoped he would be - Sam deserves to be there."
Gardiner also praised Hamilton for her "exceptional" solo skate during the semi-final and admitted that she has "always been a favourite" of his.
"She gives a phenomenal performance even when technically she's had problems," he stated. "She's had lots of things thrown at her through the series but handled them better than anyone."
> Gardiner tips Madeley for 'DOI' success