Hannah, who came fifth in last year's X Factor, turned 18 two days ago and threw a party for all her family and friends in London last night (1 May).
Tamera attended the bash along with her boyfriend Sam Callahan, as did boy band Rough Copy and Luke Friend, who came third on last year's X Factor.
Hannah held her party at The Penthouse nightclub in London's Leicester Square and had told fans beforehand that she was excited.
"Omg I'm sooo excited to see my family & friend at my birthday party later on!!!! #ThePenthouseLeicester #TurnUp!!!" she said.
While at the event, Tamera shared a picture of Hannah in the swish ladies' loos and said: "Celebrating miss @hannahbmusic birthday! You stunning girl!! X."
Luke then went one step further and shared an Instagram video of himself inside the club - while a fellow reveller busted out some moves behind him.
The singer's pal had originally posted the clip online, saying: "Last Night @hbarrettofficial Bday Bash Was Mad."
It certainly looked a mad one! Recovering today, Tamera tweeted a snap of herself snuggled up to Sam, who finished in seventh place on the ITV show.
Alongside it, she simply wrote: "Morning!"
Watch the video Luke shared here: