According to the Ladbrokes Affiliates blog, the Scot has received over 80% of all eviction bets so far this week.
PA also ranks Karly's odds as 1/8 favourite to lose out on the public vote to three other nominees.
Karly and Noirin were nominated by their fellow housemates, joining Sophie and Siavash, who were put up for failing their punishment for rule-breaking.
The Dubliner is second favourite to go, with odds of 9/2, while Siavash and Sophie have odds of 40/1 each.
Ladbrokes spokesman Nick Weinberg said: "Karly needs a miracle.
"At least she doesn't have to face Freddie - which would have sealed her fate. Even so, she's got her work cut out."
Freddie, who has so far survived five evictions, remains favourite to win the show with odds of 15/8.