The portrayal of corrupt and violent law enforcers in the show, called The Shield, angered the Los Angeles police department and sparked an advertising boycott.
The critically acclaimed series first aired on a small American cable channel, where it quickly attracted top ratings.
But when family television campaigners protested against the programme, advertisers such as Burger King, MasterCard and the US military withdrew.
Channel 5 said it hopes the show will help it build a reputation for quality American programming.
Emmy nominee
The series stars Michael Chiklis in the role of Detective Vic Mackey, who heads a team of corrupt police officers working in a violent Los Angeles neighbourhood.
Chiklis earned an Emmy nomination last week for his portrayal of the anti-hero.
His character that steals cocaine and kills an undercover officer, but also gives food money to a prostitute-informer with a child and goes home each night to his wife and autistic son.
The show, which launched in the US in March, has been described as one of the most talked-about programmes in America.
Critics have compared it with The Sopranos and LAPD Blue.
Reputation building
Channel 5 acquired a string of quality US programmes in the last year, in an effort to upgrade its image.
Forensic police series CSI: Crime Scene Investigation is among its top-rated shows, with police drama Law and Order performing respectably in the following time slot.
"What we are trying to do is identify signature shows that will do well for us," Jeff Ford, Channel 5's head of acquisitions, told The Guardian.
"CSI was the first of those and hopefully The Shield will be another.
"It's going to take us to another level of drama - the LAPD hated it, advertisers didn't like it. This is slightly unsafe drama."
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