Prosecutors made the accusation against Kristin Davis while announcing her arrest on charges of distributing and possessing a controlled substance.
Davis is accused of selling prescription pills containing controlled substances, including oxycodone.
Davis, 38, was to appear in court later Tuesday. Her attorney, Daniel Hochheiser, declined comment.
The long-shot Libertarian candidate, who has a previous conviction for promoting prostitution, has made news by claiming to have gotten call girls for Spitzer before a prostitution scandal forced him from office. But the claims have never been proven.
"As alleged, Kristin Davis sold dangerous and highly-addictive prescription pills to a known drug dealer on repeated occasions in exchange for cash," Manhattan U.S. Attorney Preet Bharara said. "Prescription drug abuse is the fastest-growing drug problem in this country, resulting in more overdose deaths than heroin and cocaine combined, and this Office has a zero tolerance policy towards anyone who helps to spread this plague at any level."
Davis was arrested at 6:30 a.m. at her home on the Upper East Side.
From 2009 to Fall 2011, Davis is accused of buying and selling drugs at house parties. She was running for governor during that period of time
Davis got into the comptroller race before Spitzer, running on a platform to legalize and tax marijuana as a way to close potential city budget gaps. Other candidates include Manhattan Borough President Scott Stringer, also a Democrat, and Republican John Burnett, a former Wall Street executive.
According to a criminal complaint, Davis began buying Xanax, Adderall and Ecstasy from the unidentified drug dealer in 2009. She allegedly told the dealer that "she provided these drugs to others at house parties," the complaint says.
In 2011, Davis asked the dealer if he would accept Adderall in exchange for Ecstasy, the complaint says. After that, they traded 240 Adderall pills for 120 Ecstasy tablets, it says.
Authorities arrested the dealer in December and he agreed as part of guilty plea to record his conversations with Davis, the complaint says. In a recorded meeting on Jan. 7, the cooperator paid Davis $675 in cash for 215 pills, it says.
"Ok, and this one is Ambien. There are 30 of those," Davis allegedly said on tape.
Authorities also alleged that in April, Davis brokered a deal for another person to sell 180 oxycodone pills to the cooperator. The complaint references a video that shows Davis bringing the person to the dealer's apartment, where the dealer used $3,600 provided by the FBI to make the purchase.
The Spitzer campaign declined comment on Tuesday.
If convicted, the 38-year-old Davis could face up to 80 years in prison.
She previously was convicted of promoting prostitution. She claims to have provided call girls to Spitzer, which has not been proven.
Some information from The Associated Press