The 'Smile' singer announced on Twitter that she was "running very late" early in the evening, yet two hours later was still not at London's O2 Arena for the ceremony.
New mother Cooper's chaotic night began when she forgot to take precautions against her dress being ruined, not wanting a repeat of an incident on Tuesday (February 19) when she neglected to use nipple pads and told followers: "Me tits are leaking. #coldandwet #notLOL."
She wrote yesterday: "Was en route, but despite numerous reminders forgot nipple pads, had to turn around. #BRITs2013 #carryon."
Things went from bad to worse when Cooper instructed her driver to take her to the Earls Court Exhibition Centre, forgetting that the Brits moved to the O2 back in 2011.
"Oh according to my driver the #BRITs2013 are no longer at Earls Court , this should only delay me by another hour or so. #whoops," she tweeted, adding later: "I can see the 02 but stuck in traffic."
Luckily, Cooper was able to at least join in with the celebrations at the Warner Music Group post-Brits party at London's Savoy Hotel, wowing at the star-studded bash with her tweed outfit.
Photo gallery - the Brit Awards:
Copyright: PA Images Ian West/PA WireShe was also photographed with husband Sam Cooper at the Sony Brits after-show party, attended by the likes of One Direction, Little Mix, Paloma Faith, Alexandra Burke and Noel Gallagher.
Cooper had earlier mocked the expected tabloid reaction to her Brits appearance, tweeting: "Looking forward to 'flaunting my post pregnancy body' and 'showing off my curves' whilst 'pouring myself into a dress' tomorrow #BritAwards."
Watch Little Mix, Labrinth and Ed Sheeran chat to Digital Spy at the BRIT Awards below: