Pauline Sullivan, 41, fell after stepping off a mat on to a tiled floor as she walked through Dunnes Stores in Cumbernauld, Lanarkshire.
The bank worker was rushed to hospital and had to be given morphine for pain relief after dislocating her left knee and suffering severe ligament damage.
Miss Sullivan remained in hospital for a week following the accident in November, 2015, and had to undergo two operations.
The mum-of-one was off work for five months and had to use mobility aids to help her walk.
She lodged a damages action against Dunnes Stores at Scotland's Personal Injury Court alleging that they were negligent.
The company claimed she had contributed to the accident as she was looking in her bag for car keys when she slipped.
However, this argument was rejected by Sheriff Peter Braid who found the store was solely to blame and ordered them to pay Miss Sullivan £41,835.55.
Issuing his written judgement, he said: "The tiled floor at the entrance of the premises presented a slipping hazard to visitors when wet.
"The state of the premises was hazardous by reason of moisture on the floor. The defenders knew or ought to have known that if moisture was on the floor, it represented a hazard to persons walking on it.
"The defenders failed to take reasonable precautions to eliminate or reduce the risk thereby created.
"The pursuer was walking at a normal speed through the store. There was, on the evidence, nothing to alert her to the fact that the tiles between the end of the mat and the doors could be slippery.
"The fact that the pursuer was momentarily looking in her bag for her car keys is nothing to the point. Even had she been
looking ahead, she may have noticed that the mat came to an end but that was not an obvious hazard.
"There was nothing there to be seen. There was no means of getting to the door other than by walking over the tiles. There was no handrail to hold on to.
"The pursuer’s momentary inadvertence did not cause her to fall, nor contribute to her slipping in any way and I am therefore unable to hold that there was contributory negligence on her part to any degree."
The court heard it had been raining on the day of the accident and staff at the clothing and homeware store could have avoided it by moving the mat to the door to cover the wet tiled area.
Miss Sullivan was said to have made a good recovery from her injuries but no longer had the confidence to resume hobbies such as running and ice skating.
The accident has also left her with a 50 per cent chance of developing osteoarthritis within the next 10-20 years which could mean she requires a knee replacement.
Sheriff Braid added: "On any view, the pursuer suffered a severe knee injury and it was described as such by an eminent orthopaedic surgeon.
"It involved not merely dislocation of the pursuer’s left knee, but multi-ligament damage.
"It was excruciatingly painful. It rendered the pursuer immobile for several weeks; and unable to resume her normal daily activities for three months."
Dunnes Stores were approached for comment.