An 11-year-old Bronx boy saved his mother’s life — picking up a kitchen knife and stabbing a burglar as he attacked her — and the two later came face-to-face with him again in the emergency room, authorities said.

That’s where he and his mom identified suspect, Brian Febus, 22, whom cops and medical staff were unknowingly treating as an innocent stabbing victim.

The career criminal was promptly placed under arrest for felony assault and burglary, according to police.

When he arrived at St. Barnabas Hospital on Tuesday night, he told staff that he had been targeted in a street fight earlier in the evening, causing cops to investigate.

Officers were already in the emergency room when Denise Soto and her son rushed in and explained what happened to them, police said.

They claimed that a man — who unbeknownst to cops, was Febus — showed up on their doorstep at around 5 p.m. Tuesday, asking to use their bathroom. Soto said she refused, sparking him to kick the door in.

She immediately darted into her kitchen and grabbed a knife, but the intruder snatched it right out of her hand, allegedly cutting her in the process.

Cops said he then pummeled the mother repeatedly, busting her lip and injuring her arm as her son watched in horror.

Fearing for his mother’s life, the brave boy grabbed the phone and tried calling 911.

The suspect spotted him and snatched the child by the arm, cops said.

After letting him go, the boy grabbed another knife and stabbed the man in the back — causing him to run off bleeding.

Police said that once the officers at St. Barnabas heard Soto’s story in full, they put two-and-two together and realized that their stabbing victim was actually the suspect who attacked her — and arrested him on the spot.

Febus, who has 14 priors, was later charged with felony assault and burglary.

He has apparently refused to answer questions and has requested a lawyer.