Tran Thi Kham, 40, did not discover the truth until after leaving her employer.
Their reunion only came about because she mistakenly left some keepsakes at his home, which he had given to her mother more than 40 years before.
Tsai Han-chao, 77, said he could not help crying when he found out he had a daughter he never knew about.
"Life's ups and downs are just like television drama. How could I have ever dreamed that she is my daughter? I couldn't stop crying when we were finally united," he told Taiwan's TVBS cable news channel.
Ms Tran had travelled to Taiwan a few years earlier to search for her father.
Her only clues were a gold ring and a photograph of him as a young man.
He had given the mementoes to a Vietnamese woman he had fallen in love with in Hong Kong in 1967. She had returned to her home country to care for her mother and he later returned to Taiwan.
The woman gave birth to Tran Thi Kham, but died two years later. The child was brought up by her aunt - whom she thought was her mother until the day of her wedding, at age 21.
On that day, her aunt revealed the true story and passed on the ring and the photo.
Much later, after bringing up her own children, Ms Tran decided to search out her father in Taiwan.
She took a job with a man in the capital, Taipei, caring for his ailing wife.
When the wife died, seven months later, Ms Tran moved on to other employment on the Taiwanese island of Kinmen.
But she realised she had left the prized possessions behind and enlisted the help of Kinmen police.
They contacted Mr Tsai and asked him to search for her things. Police described him as "stunned" to come across the keepsakes he had given his lover so long before.
He flew immediately to Kinmen, where his daughter was newly employed, for an emotional reunion.
"This is incredible and really touching to see the father and daughter get together after all these years," said Kinmen policeman, Ku Ker-ya.
Wednesday, January 23, 2008
Maid finds employer her long missing father
at 11:32 AM