"Thanks to the people around me I realised in 2003 that banned substances was not the path I wanted to follow, the 37-year-old said.
"I will give anti-doping bodies and relevant commissions all further information," Niermann was quoted as saying on the federation website (www.knwu.nl).
The federation said the rider, who retired last year, admitted to using EPO "several times" between 2000-2003.
"I went through hell and back the last few weeks, but I decided that this is the only possible way to go for me," said Niermann, who competed in nine editions of the Tour de France.
Niermann is the latest of several German cyclists to have used banned substances.
Jan Ullrich, Tour champion in 1997 and three-times runner-up to Lance Armstrong, was found guilty of doping by the Court of Arbitration for Sport last year in relation to the Operation Puerto blood-doping scandal that engulfed cycling six years ago.
He was banned for two years and CAS annulled his results from 2005 until his retirement two years later.
Former Rabobank rider Thomas Dekker, suspended for two years in 2009 for doping, said last week he would give the Dutch Anti-Doping Agency the full extent of his knowledge about cheating.
Cycling has long battled a doping problem and this month American Armstrong admitted to using banned drugs in all of his seven Tour de France victories after the International Cycling Union stripped him of his titles last year.
- Addiction & Substance Abuse
- Sports & Recreation