Kerry Launders, 29, took the spooky shot after visiting Norwich Cathedral with partner Simon Tobb, 30, and her children Millie, two, and Oscar, one.
When she looked at pictures taken on her mobile phone back home she saw the creepy figure captured on an upper level of the allegedly haunted 11th-century building.
The "apparition" appears to wear long robes and a tall hat like a bishop.
Ms Launders, from Bury in Greater Manchester, believes it could be one of 12 or so bishops buried in the cathedral.
She said: "It was my first time in a cathedral and it was really nice.
"There was nothing up there.
"But when I look back through my photos I saw something and had a proper look and I thought 'wow' this is a good picture.
"It looks like a bishop - and there are a lot of those buried there - with the long clothing and the tall hat.
"I wasn't scared when I saw it though because I believe in this sort of stuff."
The Grade-I listed cathedral is reputedly haunted and a number of ghost tours have it as a focal stop-off point.
People, including workers on surrounding building sites, have reportedly seen objects moving on their own or heard strange noises.
Visitors have also claimed to have seen other ghostly figures inside the cathedral.
There have been a glut of realistic looking ghosts caught on camera in recent months - but many have been put down to "ghost apps" available on mobile phones.
These allow users to import a ghostly figure into their own picture then blur and edit them to blend them in, giving genuine paranormal researchers a real headache.
But Ms Launders insisted this was a genuine snap.
She added: "I was just taking photos of the arch on my camera and that was that."
Some who have seen the image believe it is just an optical illusion caused by light hitting another part of the building's stonework.