'Skyscraper' singer Sam, who is expecting her third child with husband Craig Pearson, performed at the gig on Saturday (2 August) in Preston Park.
The 37-year-old looked ready to pop as she covered her bump in a glittering top teamed with black leggings.
A glamorous Sam delivered an energetic performance and showcased her powerhouse vocals, singing the likes of 'Superwoman' and 'And I Am Telling You'.
This year's Brighton Pride theme was 'The World's a Disco', to celebrate the dance, music and colour of the globe. Sam was just one of the scheduled acts at the festival, alongside boy band Blue and singer-songwriter Katy B.
I AM OFFICIALLY ON MATERNITY LEAVE AS OF TODAY XX :-)— Sam Bailey Official (@SamBaileyREAL) August 3, 2014
Despite winning the 10th series of The X Factor last year and topping both the singles and album charts with her debut releases, Sam said performing at the festival had made her feel "famous"!
After the show, Sam tweeted: "Absolutely loved @PrideBrighton tonight I actually felt quite famous, lol lovely crowd! Thanks for being awesome #freedomtolive."
An excited Sam then told fans on Sunday (3 August): "I AM OFFICIALLY ON MATERNITY LEAVE AS OF TODAY XX :-)."
Last week, Sam updated fans on her pregnancy by sharing a new HD scan photo of her unborn child. Captioning the photo, she simply said: "Had a great scan @miracleprogress today! Thanks girls."
Sam and Craig, who are expecting a baby daughter, are already parents to son Tommy and daughter Brooke.
The former prison guard announced her pregnancy in March, explaining that she found out she was expecting after taking a pregnancy test in her local supermarket. Sam's X Factor mentor Sharon Osbourne will be godmother to her child.
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