"I've doped, I've admitted that fully and wholly. I'm saddened by it and I wish I could go back and undo it," Tinkoff-Saxo sporting director Sørensen told the Danish daily BT on Monday.
"It was in the early years of my career and it's more than 10 years behind me. It was my own decision to do it."
Sørensen's admission comes on the eve of a Danish Anti-Doping Authority (DAA) report which is due to be published on Wednesday.
A Danish national road race champion between 2003 and 2011, and a stage winner at the Tour de France (2009) and Vuelta a Espana (2005), Sørensen retired last year and remained with the Tinkoff-Saxo team.
He denied that his former team boss Bjarne Riis, the 1996 Tour de France champion, was involved in encouraging him to dope in any way.
"I have told ADD about my own experiences. I have done that to relieve my own conscience and also because I wanted to help cycling," Sørensen said.
The report has already been criticised by Danish rider Michael Rasmussen who said testimony regarding Sorensen's doping had been omitted in an effort to protect him.
Tinkoff-Saxo statement on Nicki Sørensen
Tinkoff-Saxo has supported the cooperation and collaboration by all its members with any entity involved in creating a better environment in professional cycling. The team believes that a full disclosure of negative past practices should be encouraged in order to identify and implement appropriate measures to prevent wrongdoing in the present and future sport.