The hapless crook can be seen with the 7ft long (2.1m) blind clearly sticking out from the top of his coat as he tries to make a getaway from a Dunelm Mill store.
Police say the suspect entered the shop at around 2pm on Sunday (16/10) before concealing the Venetian blind down one trouser leg and up the back of a jacket.
He then left the premises based at the Nene Valley Retail Park, in Northampton, without paying for the item in front of baffled workers.
And after staff noticed his suspicious bulge they followed him up a nearby canal path, where he dropped the blind before escaping empty handed.
Yesterday (Tue) Northamptonshire Police released two CCTV images of the suspect in a lift, showing the blind protruding from his green jacket above his head.
A force spokesman said: “Officers would like to speak with the man pictured or anyone with information can contact Northamptonshire Police on 101.
“Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.”
Web users took to Facebook to comment on the police appeal with one writing: “This has got to be Britain’s dumbest crook.”
Another local resident added: “How on earth was he thinking he could get away with that? What a moron.”