Tamati, also known as "Sandy", pleaded guilty to supplying methamphetamine and possessing utensils for the Class A drug at the start of the trial.
Crown prosecutor Steve Manning told the jury the woman, then aged 19, knew all three males, and couldn't repay the accused. She was therefore kidnapped in the early hours of November 26, 2016.
In a thread of Facebook messages read in court, the jury heard Tamati and the complainant discussing "the bill"; him telling her to come see him and "work it off".
The Crown alleged she was delivered to a small sitting room occupied by Tamati who then assaulted and sexually violated her.
In a DVD interview the complainant said Tamati threatened her with scissors, tapping them on her head as he told her he should cut off her hair and stab her.
Defence counsel Russell Fairbrother QC warned the jury there was a danger in thinking that Tamati, who took the stand to refute the allegations yesterday, was dishonest just because he was a senior gang member.
But Manning said a senior gang member would be "the last person" someone would make false allegations against.
In his summing up, Judge Tony Adeane told the jury it was important to decide the case in a "calm and dispassionate way", particularly when the trial involved sexual allegations and gang undertones.
After deliberating for two hours, the jury returned with unanimous guilty verdicts on all 11 charges two hours later.
Tamati was remanded in custody to be sentenced on December 15, along with Benson and Henare.