Edwards, 27, posted the snap on Twitter earlier this week via the official Little Mix account, writing: "Dw didn't get any mud on the carpet [smug face emoji]."
In the image, the singer seen lounging on a carpeted staircase wearing an all-white outfit, staring down at the camera.
But if you look a little closer, at the top of the stairs you can see a woman with what looks like a vacuum cleaner, supposedly waiting for Edwards to take her shot.
Twitter user Mart Tweedy retweeted the picture, writing: "Crying at the cleaner waiting to do the stairs, top left."
Tweedy's post has since gone viral, racking up more than 100,000 likes and thousands of retweets.
"That's a great spot," someone commented, adding a crying-with-laughter emoji.
Another person wrote: "F***ing hell well spotted."
A third said: "LMAOOOOOOOOOOOOOOOOOOOOOOOOOO."
Many others commented to say the photobomber had 'ratioed' Edwards - a term for what happens when someone's response to a tweet receives more likes than the original post.
In this case, Edwards' photo has been liked around 42,000 times, with a little more than 3,500 retweets.
Tweedy's quote-tweet, however, has pretty much doubled her stats.
"THE RATIO," one person said.
Another joked: "Not perrie getting ratioed by the cleaner hsjdjc."
Edwards had also posted the photo on Instagram, where it was part of a set with another similar snap.
The other picture, however, didn't feature the cameo from the cleaner, meaning she must have wandered into the shot mid-way through Edwards' staircase photoshoot.
Still, forgetting to crop someone out of a photo isn't quite as bad as another faux-pas Edwards once made - having accidentally sent 'really naughty' messages to her ex-boyfriend's dad.
The star, who once dated One Direction's Zayn Malik, spoke about the mishap in an interview on The Jonathan Ross Show, telling host Jonathan Ross she couldn't even divulge what the messages said, as they were too racy.
Edwards recalled: "[I sent some to] my ex-boyfriend's dad... by accident. It was the most mortifying moment of my entire life.
"I sent a selfie of my face and loads of messages. I can't even say [what the messages said]. Like really naughty ones. Like really, really naughty messages."
She added: "His mam messaged the next day to say 'the iCloud is still connected'. It was the most mortifying thing ever, but kind of funny."