Paul Burrell, who the late royal referred to as her "rock", has joined the Channel 5 reality TV show for a few days to show the American housemates how to be good servants to their British rivals, who are set to become members of the reality TV show's Royal Family this week.
However, viewers have taken to Twitter to slam him for "cashing in" on his royal connections.
Comments included: "Nice to see/hear that Paul Burrell is still cashing in on his fame as Princess Diana's butler."
"Paul Burrell still cashing in on Princess Diana's death... #shameful #CBB" and "Urgh. Paul Burrell still cashing in all these years later :/ #CBBUK (sic)."
Other horrified Twitter users wrote: "I can't stand Paul Burrell. Still trading off Princess Diana and betraying palace secrets" and "I see that Paul Burrell is still using Princess Diana to boost his own fame. He's so shameless! #cbb (sic)."
And many people were horrified that his appearance on the show came just one day after the 18th anniversary of Diana's death on Monday.
Viewers wrote: "Absolute disgrace having Paul Burrell in the house 18 years yesterday since princess Diana died" and "The day after the 18th anniversary of Princess Diana's death, Paul Burrell enters the CBB house. I think that shows what kind of man he is (sic)."
Princess Diana died after a car crash in Paris on August 31, 1997.