The Staten Island assistant principal accused of slashing his wife’s former lover still has one big booster — his dad.

Vincent Scotto’s father sprinted up the stairs of Staten Island Criminal Court on Monday to bail him out moments after the educator’s arraignment.

Scotto, 43, was charged with felony assault and weapons possession and was joined by his parents, wife and a friend as he was arraigned. He pleaded not guilty.

After learning that his son would be granted $5,000 bond, Scotto’s dad darted out of the courtroom and up the stairs before immediately coughing up the $2,500 to have him released.

“He’s a hard worker, he’s a family man, he takes care of his kids,” said Scotto’s lawyer, Joseph Mure Jr. “He has been in the school system for 20 years.”

Prosecutors painted a much different picture of Scotto, saying he savagely sliced 59-year-old John Carosella with a razor blade as he sat in a car outside his house.

“The victim was stabbed during a razor attack, he was stabbed in the chest, arm and right hand,” said Assistant District Attorney John Hall. “The victim had to have stitches and staples, as well as surgery.”

Carosella has allegedly been harassing Scotto’s family for years — driving past their house at all hours and screaming “Whore!” — ever since Scotto’s wife ended their long-term affair two years ago.

During the arraignment, Mure revealed Carosella was unable to select Scotto out of a lineup, but prosecutors claimed it was because “he did not have his glasses.”