Hamilton, 51, will face the public vote alongside The Hills stars Heidi and Spencer, who entered the Channel 5 show as one contestant, after receiving the most nominations from their fellow celebrities.
Champion jockey Dettori was already up for eviction after four contestants living in the basement were told they had the chance to move to the luxury living quarters upstairs.
In order to do so they had to nominate one of the group to face the public vote.
Nominations were be screened on last night's episode ahead of the first live eviction show on Wednesday.
Dettori was chosen to face the public vote after his fellow basement dwellers, X Factor singer Rylan Clark, footballer Neil "Razor" Ruddock and actor Sam Robertson, decided he was popular with viewers and therefore more likely to survive the public vote.
As a result of their decision the quartet were freed from living in squalid conditions to join their fellow contestants in the main house.
Hamilton was allowed to leave the basement earlier this week after falling ill.
Asked how he felt about being up for eviction, Dettori said: "A little bit scared, but hopefully the British audience will vote for me to stay in."
Clark has been installed as favourite to win the show by bookmaker William Hill, with Dettori next.
The contestants have spent their first few days holed up in the custom-built property in full glare of TV cameras, with a winner emerging later this month if they can prove popular enough with viewers and their own housemates.
It is the fourth series of Celebrity Big Brother screened by Channel 5 in the space of 18 months after it resurrected the show which was dumped by Channel 4.
Ratings have fallen since it left its original home with the most recent series drawing an average of 2.3 million viewers, the lowest audience yet.
It was almost three million down on the 5.2 million average for the first series in March 2001.