The pair had been 'fake' evicted on Friday night and have lived in the secret attic ever since, watching the other housemates and messing with them in a series of tasks.
Yesterday in the house, Big Brother gathered the group for an announcement.
"Housemates, for the last couple of days you have bee tested by the viewers in order to prove yourself worthy of staying in the Big Brother house and becoming a Big Brother finalist," Big Brother began.
BB continued: "However, what you didn't know is that there were only two viewers testing you.
"Housemates, you should remain silent and face the screen."
Big Brother then played a video of Hannah and Tom's fake eviction before they re-entered the main house.
You can watch the reaction to the pair's return in the video above.
And in making their surprise comeback, they dropped a nomination bombshell as they revealed that Charlotte Keys and Isabelle Warburton were up for the axe.
Charlotte and Isabelle face the chop in the last eviction of the series after being voted for in secret by Tom and Hannah who were fake evicted from the house on Friday night.
Hannah put Charlotte up for eviction, saying: "She is going to be my option of nomination. The reason being is because I feel like she should have respected the fact of how it may feel nominating another person that is a pair when you've been in that situation."
Tom then nominated Isabelle for eviction, saying: "She's nominated me twice and evicted me, so yeah I'm going to nominate Isabelle."
Other than an apparent mock shock face from Charlotte, there didn't appear to be much immediate reaction from either of the girls.
The one with the most votes to evict will be booted out the backdoor TONIGHT, with their exit shown in Tuesday night's episode.
Big Brother continues at 10PM this evening with all the fallout of Hannah and Tom's return to the house.