Investigators said Xiong had eight firearms in the family's Cedar-Riverside home when the boy discovered a 7.62 caliber semi-automatic pistol tucked under a pillow in an upstairs bedroom and accidentally shot the toddler.
Two-year-old Neegnco Xiong died before he could be transported to the hospital.
According to WCCO, prosecutors said the gun lacked a working safety and was one of several weapons police found improperly stored in the home--a violation of Minnesota law.
Xiong was found guilty on four criminal counts, including two counts each of manslaughter and child endangerment. He was acquitted of one count of gross misdemeanor child endangerment.