It was her first performance with The Saturdays since she announced she is expecting her first child with boyfriend Ben Foden.
But Una Healy didn't show any sign of toning down her stage outfits, as she performed with her bandmates wearing a sexy leather corset and sheer black skirt.
The 29-year-old singer looked as slender as ever as she delighted fans with the performance, her corset hiding her ever-growing baby bump.
Yummy mummy! Una Healy took to the stage with The Saturdays wearing a leather corset and sheer black skirt
Blooming: The 29-year-old singer recently announced she is three months pregnant
Una, who was singing with The Saturdays in celebration of Arthur's Day in Dublin, Ireland, announced earlier this month that she and England rugby player Ben will soon be starting a family.
And Una's Saturdays bandmate Rochelle Wiseman has revealed the singer is so far 'sailing through' her pregnancy.
She said: 'Una's been so lucky, she's kind of made the whole process seem easy.
Ladies in black: The Saturdays looked chic in their matching outfits
Belting it out: Frankie Sandford highlighted her tiny waist in her all-black number
'All those women out there who have struggled through their pregnancy will be like "I hate her" because Una's sailing through.'
But the flame-haired mum-to-be confessed strong smells were making her a bit queasy.
She said: 'So far so good. Smells are a challenge though - if I smell something that's not great, I just start going "Ugh".'
Meanwhile, the rest of The Saturdays - who surprised fans with an acoustic set in a Dublin pub before performing at the Guinness Hopstore - insisted they weren't feeling broody just yet.
'Una hasn't even given birth yet, so let's just leave that to Una for now,' Rochelle said.
Bandmate Frankie Sandford added: 'We'll get to play with (Una's baby) when it's happy and when it cries we'll get to give it back.'