The mother-of-two went for a glamorous all-black ensemble for the gig at the Phones 4u Arena in Manchester on Saturday night (5 October).
Coleen teamed a pretty black shirt with an embellished collar with a short skater-style black skirt that showed off her tan. She kept her hair simple, tied back in a glossy ponytail, but went all out with a gorgeous smoky eye.
Interestingly, one Twitter user remarked that Coleen always seems to wear black, prompting the star to reply: "Love black… time of the year when all the nice stuff seems to be in black!! I like colour too!"
Leaving her husband and sons at home for the night, the fashion designer looked to be in high spirits as she arrived at the arena clutching her tickets.
And clearly she was just as happy when she left, tweeting afterwards: "Bruno Mars was brilliant tonight!! What a talent!!"
She also retweeted a friend who joked Bruno was so great she was planning on seeing him again in Liverpool: "Well Bruno Mars was unbelievable in concert last night, love the way he dances! Had a ball, think I'll be going the Echo as well to see him."
Coleen, who is married to Manchester United player Wayne Rooney, has had a busy few months after giving birth to her second son, Klay Anthony, in May.
Not only is she looking after two small children (son Kai is three), she's also just released a brand new collection for Littlewoods.
But just because she's a celebrity and a fashion designer doesn't mean she's felt the pressure to lose her baby weight quickly.
She said last week: "My top tip for new mums is to not worry about your appearance, certainly not during the early stages. The pressure on mums is too high and we all just need to relax and enjoy these precious moments without fretting about fitting in to our jeans."
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