Williams, most famous for his role as Omar on HBO’s The Wire, was found dead in his Brooklyn flat in September 2021.
The four men are accused of narcotics conspiracy. Police say they sold drugs laced with fentanyl, a synthetic opioid blamed for thousands of drug deaths.
A medical examiner has ruled that the 54-year-old’s death was an accident.
The suspects include Hector Robles, Luis Cruz and Carlos Macci – who were all arrested on Tuesday and are expected to make their first court appearances on Wednesday.
Irvin Cartagena was arrested on Tuesday in Puerto Rico and is expected to go before a judge on Thursday.
“This is a public health crisis. And it has to stop,” US Attorney Damian Williams said in a statement announcing the arrests.
“Deadly opioids like fentanyl and heroin don’t care about who you are or what you’ve accomplished. They just feed addiction and lead to tragedy.”
Investigators have obtained surveillance footage of the men allegedly selling drugs to Williams on the street the day before he was found.
Police have obtained footage of the alleged drug deal
They allegedly continued to sell the drugs at residences in Manhattan and Brooklyn even after they learned that their drugs had killed Williams, officials say.
According to the Daily Beast, NYPD detectives treated his death as a homicide, and used surveillance cameras throughout the city to trace car licence plates to the suspects.
“Treat this case as if Michael K Williams was hit by a bullet,” one police official instructed his officers, he later told the website. “Make believe he got shot.”