Mrs Thornton, 85, was tracked down by The F.A after they saw a picture of her celebrating wildly on the front row as Phil Parkinson's men defeated Premier League Chelsea at Stamford Bridge in the F.A Cup Fourth Round just under a fortnight ago.
The picture was originally spotted online by one of Mary's sons, John, before The F.A also took note of the image and were won over by Mrs Thornton's passion for the Bantams!
The image in question, along with those of Mrs Thornton and the F.A Cup used in this article, was taken by club photographer, Thomas Gadd.
Complete with two security guards, the world-famous F.A Cup trophy was brought up all the way from F.A headquarters at Wembley Stadium and into the front room of Mary's Bradford home on Thursday lunchtime.
As a member of the Shipley Bantams, Mrs Thornton regulars attends home and away City matches.
A delighted Mary said: "Who would have thought that the F.A Cup could be in your house? It is a huge honour.
"It is just unbelievable, and a rare privilege.
"I just hope it isn't the last time we see the cup in Bradford!
"The Chelsea game was magic - all of the goals were beautiful. I've watched the footage back from the match so many times.
"I had only just got over the Chelsea game and now this comes along - I won't sleep for a week!"
FA Cup press officer Matt Phillips added: “I was looking back over the footage of Bradford City’s win at Chelsea and could see Mary celebrating on the front row at Stamford Bridge.
“BBC pundits like Robbie Savage were saying it was the biggest upset in FA Cup history so it seemed like a good idea to mark that shock result by taking the trophy into the local Bradford community and Mary seemed the perfect choice."
“Mary is clearly well known at Valley Parade as the club knew who I was talking about almost straight away when we were trying to make contact.
“The FA Cup doesn’t make many house visits so we hope Mary and her friends and family enjoyed an afternoon with one of the most iconic pieces of silverware in sport.”