Her son keeps telling her to stop, but she insists nobody else can do the job to her high standards, and carries on with death-defying cleaning routine.
“It’s important to keep your house and windows clean. Any woman will tell you that,” said Mo, a mum-of-three, who keeps fit by practising Tai Chi every morning.
She was snapped by a satellite dish installer who posted his pic of her online, captioned “window cleaning Glasgow style”.
Mo, who moved to Glasgow from Hong Kong 25 years ago, even once had to be rescued by a neighbour after locking herself out on the ledge.
“Nothing gets between mum and her housework,” Mo’s son Alan said.
“No matter how often we tell her not to go on to the window ledge, she ignores us. When we clean the windows she says it’s not to her usual standard. That’s mums for you.
“Even after being locked out she refuses to take heed of anything we say.”
Mo lives in a fifth-floor flat towering above Sauchiehall Street.
She was cleaning her windows as per usual last week when Kieran captured the terrifying image.
He captioned it “window cleaning Glasgow style” and it was shared hundreds of times on sites like Twitter and Facebook.
Kieran said: “I was putting an aerial up on the next block when I turned and saw her cleaning the sill. By the time I got my phone out she was, to my amazement standing, on the wet surface.
Son Alan gets the fright of his life every time Mo pops out on to the ledge as she doesn’t wear any sort of safety harness.
He also recalled how she was once left outside after the window slammed shut.
“A neighbour had to come to her rescue by coming into her flat and opening the window to let her back in,” he said.
Visitors to her tidy flat are asked to remove their shoes. Inside they are treated to a panoramic view of Glasgow through crystal-clear windows.
The superfit mum-of-three - who keeps in trim by practising Tai Chi every morning - said: “I also walk everywhere and believe that if you keep moving you keep living.”
Mo is one of eight surviving children of a Hong Kong farmer and spent her early years helping harvest crops.
She survived the Japanese invasion of 1941 so window-cleaning holds few fears.
She is a popular member of the Chinese community in Glasgow’s Garnethill area.
“I suppose I should listen to my children’s plea to stop washing my windows,” she said.
“But I have never been frightened of heights or hard work.”
Mo Kam Tai (left) was snapped by her neighbour as she climbed out onto a fifth floor ledge to clean her windows.