British Swimming chief executive David Sparkes had said Daley, who won bronze in the men's 10 metre platform at last year's London Games, was "putting the cart before the horse" with his role in ITV show Splash.
Sparkes said Daley had "yet to achieve his full potential" in the sport but his proud parent hit back.
Rather than criticise her son, who was one of only three British medal winners in the pool, Debbie Daley said the governing body should be grateful for his success rather than question his commitment.
"Tom was one of the few major success stories for British Swimming this summer... and possibly one of the athletes that helped you retain your job," she said in an open letter to Sparkes, published in the Daily Mail.
"Surely you should be thanking Tom and showing your support and gratitude?"
Debbie Daley said her son's decision to appear in the show that features celebrities diving had not impacted on his professional commitment.
She highlighted the fact that he competed in the world junior championships in Australia in October, winning two golds, while many of his TeamGB team mates were celebrating their Olympic success.
"For an individual who is normally so motivated, going back to intense training after the climax of the Games was a real struggle," she added.
"Everyone else was taking long holidays, partying, celebrating exams, while Tom had to get straight back to diving. You must remember what you did the summer you were 18 years old?
"However, Tom didn't want to back out. While the competition had no real incentive for him, Tom had made the commitment to his performance director Alexei Evangulov and to British Diving and - despite me trying to convince him otherwise - he got his head down and ploughed on."
Following the publication of the letter, the diver tweeted: "My mum is amazing."
British Swimming were not immediately available for comment. — Reuters