Jordan shared a moving post on Instagram, saying “my hero and best mate in the whole world” has been in and out of hospital for the previous four months.
Doctors initially diagnosed him with a stroke after he was suffering seizures, professional dancer Jordan said, but have now said he has an “aggressive” tumour.
He shared a video of his father playing with his five-month old daughter Ella.
In the post, he wrote: “We have been told that it’s not advisable to operate because of where the tumour is and wouldn’t actually make that much difference even if they could.
“The end result is, it’s terminal. They are saying with chemotherapy and radiotherapy we might be lucky and get a year with him.
“As I write this tears are streaming down my face as I’m sure many of you have the same love for your parents. This is honestly the worst time of my life.”
Jordan, who is married to his fellow former Strictly professional Ola, said he was sharing the message to get a second opinion in the hopes doctors have got the grim diagnosis wrong.
The 42-year-old said: “I’m looking to find the best surgeon to see my father as I want to know I’ve done everything possible before I can accept it.
“If anyone that reads this can advise me and my family on who is supposedly the best in this field i would be eternally grateful.
“My heart is broken.”
In April, Jordan revealed his father was diagnosed with coronavirus and told fans later that month he had been discharged from hospital and was doing “so much better”.
Strictly judge Shirley Ballas was among the celebrities sending messages of support to Jordan.
She said: “I’m soooo sorry thinking of you all at this time.”