Rapper Tekashi 6ix9ine rode the Bloods gang’s coattails to stardom ? but he was little more than a punching bag that the gang kept around as a cash dispenser, it was revealed in Manhattan federal court on Wednesday.

The rainbow-haired rhymester, 23, put up a tough persona as he glommed onto the Nine Trey Gangsta Bloods in music videos and on his Instagram account, where he eventually racked up nearly 15 million followers.

But behind the scenes, gangbangers mocked him as a poser, repeatedly calling him a “rainbow-haired s–thead,” according to testimony on Wednesday.

He hung out with the gang for his “career, credibility, street credibility, videos, music, the protection,” said Tekashi ? who turned government witness “the day after” he was ­arrested for gang ties on Nov. 19, 2018, and is now testifying against former associates Anthony “Harv” Ellison and Aljermiah “Nuke” Mack.

But the gang benefitted from the chart-topping artist’s largesse ? with Tekashi paying it for protection and picking up the tabs for champagne and girls at Queens strip clubs, law ­enforcement sources said.

Members even skimmed his take from concert performances and endorsements. “Say I would get $250,000, they would give me like $185,000 and take the rest,” Tekashi testified.

He suffered another indignity in March 2018 when his crew robbed a rival at gunpoint and then kicked Tekashi out of the car with the piece so they wouldn’t get “stitched up” if the cops pulled them over.

The rapper was miffed he was left in the lurch in a place where he was bound to be recognized.

“I’m like bro, ‘I’m f–king famous at this point,’” he recalled saying when getting pushed out. The self-proclaimed “King of New York” glorified drive-by shootings and the gangsta life in his lyrics. But unlike hip-hop stars of the past, for whom gangs were a means of survival, Tekashi came to the rap game first and infiltrated a crew later.

Born Daniel Hernandez, the tatted-up rapper grew up in a tiny Bushwick apartment on Locust Street near Broadway that he shared with his Mexican-immigrant mother and other family members. When he was 13, his adoptive father was shot down in broad daylight.

Soon after, he began acting out, getting expelled from Juan Morel Campos Secondary School in eighth grade.

He worked odd jobs, including as a delivery boy, at a grocery store working the register, as a busboy, but in 2014 he decided he was meant for greater things.

He began launching his music career and came up with his alter ego. Inspired by Japanese anime, he adopted the name Tekashi and then tagged on the suggestive “69,” a number he reportedly has tattooed on his body more than 200 times.

At first, he says his genre was more “rock ’n’ roll rap” and most of his fans ? or at least those watching his YouTube videos ? were from Slovakia. He went on a brief tour there and in other Eastern European countries in 2014, a stint that only netted him about $2,000, he said.

Tekashi’s first run-in with a member of the Rikers Island-spawned Nine Trey crew didn’t happen until the summer of 2017, while he was working on his hit song “Gummo” and met hip-hopper Seqo Billy.

Everyone in the video for the song wore red because “red is what a Blood member would wear,” Tekashi testified on Tuesday.

Through Seqo Billy, Tekashi met his future manager Kifano Jordan, aka “Shotti,” who was sentenced to 15 years behind bars in September in connection with his role as a high-ranking member of the street gang.

Tekashi began running with the gang, though he was never officially initiated.

There were holes in his image. As The Post reported last July , a red “Bloods” Chevy Tahoe that was featured in Tekashi’s “Tati” music video had a pro-cop “thin blue line” sticker on the passenger side of the rear window.

Eventually, peeved that the gang was taking too much of his earnings, Tekashi began pulling away in the summer of 2018. In July 2018, he was allegedly kidnapped by Ellison and a man identified only as “Shaw” and forced to disavow his membership in the violent street crew.

“Harv made me say, three times, ‘I’m not Billy,’?” testified Tekashi on Wednesday, referring to slang for Blood loyalists.

Tensions peaked last fall when Tekashi was at Midtown hot spot Philippe Chow celebrating dodging jail time in a years-old sex crimes case and a handler from music label 10K Projects turned away Shotti and crew.

His life was reportedly threatened on an FBI-obtained wiretap over the snub.

The rapper, whose latest album is titled “Dummy Boy,” faces up to 47 years in prison ? though his cooperation could result in a much more lenient sentence.

Additional reporting by Elizabeth Rosner