The 11-year-old boy, from Suzhou, China, is said to have sliced off the digit after having an argument with his father about his smartphone addiction.
As his father chastised him for being constantly glued to his phone, the boy is said to have grabbed a knife and plunged it into his left index finger in a fit of rage.
The argument is said to have started when his father told him to put down the phone and help his brother with his homework.
The boy was taken to hospital where surgeon Ren Zhourong attempted to reattach the severed finger during a three-hour operation.
It will be a week until doctors know if the surgery was a success.