The Brooklyn vigilante who fatally rammed his SUV into a cyclist as revenge for an alleged car break-in faced the formal justice system Tuesday as he was charged with murder.

Korey Johnson also faces a manslaughter rap for allegedly rocketing his 2003 Jeep Grand Cherokee down a Bedford-Stuyvesant street and into fleeing cyclist Donald Robert, smashing Robert into a row of parked cars and sending the SUV onto its side in a wild, caught-on-video scene.

The deadly chain of events began at around 6 a.m. Monday when Johnson and his girlfriend witnessed Robert trying to break into several cars along Marcus Garvey Boulevard, including the Jeep, according to cops.

Johnson, 41, confronted the would-be bandit, who responded by slashing Johnson’s girlfriend on the arm with a screwdriver then riding off, police said.

Johnson hopped into the car and sped off in hot pursuit, allegedly ramming into Robert along Broadway near Ellery Street, leaving Robert, 47, with fatal blunt-force trauma, according to a criminal complaint.

Johnson was wordless Tuesday, both as he was walked handcuffed by detectives from the NYPD’s 83rd Precinct station house and during his arraignment at Brooklyn Criminal Court, where he pleaded not guilty and was ordered held without bail.

Johnson’s lawyer, Arielle Simon of Brooklyn Defender Services, declined to comment after the brief hearing.

Despite 40 arrests on Johnson’s record prior to the incident — barely more than Robert’s 38 busts — a lifelong friend denied Johnson had a temper and said he was shocked by the allegations.

“I’m actually surprised. I honestly feel he was just chasing him,” said Daniel Dunkin, 30. “I don’t think he really meant to kill him.”

Dunkin, who owns an auto dealership, described Johnson as a fellow car nut whose passion was buying and tuning up used autos.

“He loves his cars. That’s his baby,” said Dunkin. “He goes to the auction and fixes them. He’s the type of guy that gets a $500 car and makes it a lady.

“The guy [Robert] cut his other lady, too,” said Dunkin, referring to Johnson’s girlfriend. “He tried to harm both his ladies.”

Additional reporting by Andrew Denney