The discount variety retailer, which operates stores under the Home Bargains fascia, discovered a wireless CCTV device had been installed by the alarm key pad of its Wigan store.
The nondescript device had been designed to blend in with the colour of the door frame and was "fairly well made" with mechanics inside roughly the same size as a 50p coin.
Fortunately, staff discovered it before thieves were able to use it to deactivate the alarm and gain entry.
"Shrinkage is a massive problem for retailers and we take a firm line when it comes to stopping it," said operations director Joe Morris. "Security at Home Bargains is a huge priority and we strive to ensure the safety of all our staff and customers. We have thorough security procedures in place at all our stores and all staff are trained on security protocol."