Former bandmates Kimberley Walsh and Cheryl Fernandez- Versini joined the birthday girl to celebrate reaching the milestone in style and had a special cake made with Nicola's face iced onto a mermaid's body, reported Female First.
After sharing a picture of the cake on Instagram, Kimberley, 33, wrote a message wishing Roberts happy birthday.
"Amazing 30th birthday party for the one and only Miss @NicolaRoberts thanks to @LoveEnt you're the best! #party #big30 #Nicola's30th... #Happy30thNicola thank you cakegenie (sic)"
The singer also posted a picture of Nicola and herself having a massive hug, captioned ""#birthdaygirl (sic)"
The only member of the girl group not to make an appearance was Sarah Harding, who was also absent when her former bandmates got together at the Pride of Britain Awards last week.