The victim Solomon Gordon suffered life-threatening injuries when he was stabbed at least four times by Nathaniel Nugent who had sneaked into his "baby mother's" home, in Suffolk Road, Wednesbury, on July 24 last year.
A jury at Wolverhampton Crown Court on Friday found the 25-year-old guilty in a unanimous verdict following a five-day trial.
Nugent, who had a difficult relationship with the mother of his son, sneaked in through a window after hearing noises coming from the premises. He told the jury he attacked Mr Gordon after climbing through an open ground floor window to find him wearing a face covering and appearing to be assaulting the woman.
The jury also heard he should not have been anywhere near the woman due to him being subject to a restraining order meant to prevent him from contacting her following previous issues.
They had agreed to meet up with the child at a pub earlier that day and had a disagreement on the way back.
In his evidence he said the taxi pulled up a distance from her new address as she did not want him to know where she lived. He said he helped her and the child out of the taxi which then drove off, leaving him standing in the street.
He claimed he did not follow her to see where she was going, but was concerned for her safety due to the late hour.
Nugent claimed he got lost as he wandered the streets, but as he walked along Suffolk Road he heard the woman's voice and that she was arguing with someone.
He said he swung his flick knife a number of times at the victim as he believed the woman and the child were in danger and he was acting in self-defence. He also said he was unaware she was seeing another man and denied he intended to harm Mr Gordon.
Mr Gordon was not carrying any weapons and both him and the woman were taken by surprise by the defendant's presence in the property.
Under cross-examination by prosecuting barrister Ben Close the defendant also said lyrics relating to drugs and gang violence on his drill music videos were part of his act and not a sign that he was prone to violent behaviour.
But the jury unanimously found him guilty of trying to kill Mr Gordon.
Nugent, of Clive Road, in Redditch, had denied attempted murder.
Judge Simon Ward thanked the jurors for their service and adjourned the matter.
He told Nugent, who has been in custody since being arrested the day after the stabbing, that he will be sentenced next month.