A "furious and shocked" Jackie Chan said he blamed himself after his son was caught in one of the mainland's highest-profile drug busts in years.
Writing on his Weibo microblog, the Hong Kong action film star admitted he had not been a good enough parent to Jaycee Chan, 32, adding: "I'm very furious and very much in shock".
The message, to his more than 22 million followers on China's answer to Twitter, was the first comment by Chan since the drugs raid that snared 32-year-old Jaycee - better known as Jaycee Fong Cho-ming - along with Taiwanese acting heartthrob Ko Chen-tung.
"As a public figure, I'm ashamed," said Jackie Chan, who in 2009 was appointed as Beijing's anti-drug ambassador.
"As a father, I'm in pain. His mother is heartbroken. [I] hope youngsters will take Cho-ming's lesson seriously and stay away from drugs."
Jaycee Chan and actor Ko, 23, were detained on August 14 when they were caught smoking marijuana at a foot massage parlour in Beijing.
Ko, also known as Kai Ko, received a 14-day administrative detention, while Chan was put under criminal detention on suspicion of "providing shelter for others to abuse drugs".
Police recovered more than 100 grams of marijuana from the home reportedly belonging to Jackie Chan in Beijing. Mainland media reported that Jaycee Chan admitted that he first abused drugs in the Netherlands in 2006, while Ko did it for the first time in Jaycee's home two years ago.
A video of the police's raid on Jackie Chan's home was shown on state television channel CCTV on Tuesday, together with Ko's tearful confession.
Watch: Jackie Chan's son Jaycee Chan arrested over drug charges
"Here, I'm telling Cho-ming: take responsibility for the mistakes you make. As your father, I'm willing to face the future with you," wrote Chan, who turned 60 in April. "Lastly, I did not teach my son well. I'm taking my responsibility and together with Cho-ming, we take a deep bow and offer our apology to society and members of the public."
His publicist refused to comment on reports he was trying to get his son out of detention in Beijing.
The Weibo post received more than 40,000 responses within 26 minutes of appearing on his feed. Many fans comforted the star, but some criticised Chan for neglecting his son because of his busy showbiz life.
"You really should reflect if you are not aware of this [drugs problem] after so many years," wrote one internet user.