Radomski was ordered by U.S. District Court Judge Susan Illston to pay an $18,575 fine after he admitted selling steroids, human growth hormone and speed to dozens of current and former major leaguers.
"These are very, very serious offenses," said Illston, who lectured that some of Radomski's best customers served as role models to children.
Radomski pleaded guilty last April to distributing steroids and laundering money from 1995 until Dec. 14, 2005, when agents raided his Long Island home.
Radomski led investigators to Brian McNamee, the former Yankees strength coach who claimed he injected Roger Clemens with steroids and human growth hormone at least 16 times from 1998-01, an allegation the seven-time Cy Young Award winner vehemently denies.
As part of his plea agreement, Radomski was required to cooperate with federal investigators and former Senate majority leader George Mitchell, who headed baseball's doping probe.
Radomski is required to continue that cooperation. He is scheduled to testify along with Clemens and McNamee on Wednesday before the House Oversight and Government Reform Committee.
"It sounds like Radomski provided a lot of information that was helpful to the government," said Earl Ward, McNamee's lead lawyer. "They rewarded him for that."
Radomski's lawyer, John Reilly, said outside court that federal officials interviewed Radomski under oath Thursday, but declined to say whether Radomski was asked about Clemens.
Radomski, who had no prior offenses, had faced no more than six months in prison. Assistant U.S. attorney Matt Parrella recommended that Radomski receive probation because of his extensive cooperation.
There's a culture of "hear no evil, see no evil, speak no evil" when it comes to steroid abuse in sports and Radomski's naming of names "is at least a first step to turning that around," Parrella said.