As exclusively revealed by Telegraph Sport on Sunday, De Jongh is the third member of Team Sky staff to leave the Tour de France-winning team after the zero-tolerance approach to doping was restated in the wake of the Lance Armstrong affair.
Sean Yates announced his retirement from professional cycling yesterday, leaving his role as senior sports director but refuting suggestions his departure was forced.
American Bobby Julich left the squad last week after revealing he took EPO in his racing career.
A Team Sky statement read: "Steven de Jongh has left Team Sky following three seasons as sports director.
"After the team reaffirmed its position on anti-doping, Steven disclosed that he had taken a banned substance earlier in his career as a professional rider."
Team Sky principal Dave Brailsford said: "There's no doubt about Steven's work with us or his approach. He's been a highly-valued sports director and colleague over threem seasons.
"Steven deserves our respect for the courage he's shown in being honest about the past and it's right that we do our best to support him.
"He has our best wishes for the next step in his career."
Yates, Julich and De Jongh could yet be joined by others in leaving Team Sky.
Brailsford and sports psychiatrist Dr Steve Peters are interviewing every team member in turn and asking them to sign a document confirming they have had no involvement in doping.
Yates, one of five Britons to have worn the Tour de France race leader's yellow jersey, and Team Sky insisted his departure yesterday was for personal reasons and "there were no admissions or disclosures that would have required him to leave the team".
Both Yates, who was key in Wiggins becoming the first British winner of the Tour, and Julich worked with Armstrong during their careers.
Armstrong was banned for life and stripped of all results from Aug 1, 1998 to leave the 1999 to 2005 Tours without a winner, following an investigation by the United States Anti-doping Agency.
Michael Barry was a key witness in the USADA investigation, with which Armstrong declined to co-operate, and spent three years at Team Sky before recently retiring and admitting to doping.
