Catherine Kieu is alleged to have thrown the severed penis into a mechanised garbage disposal unit in her kitchen and watched as it was mutilated.
She then called the emergency services.
The 48-year-old Californian has appeared in Orange County Superior Court charged with torture and aggravated mayhem, with sentencing enhancements for causing great bodily injury and using a knife.
Orange County prosecutors say the incident followed an argument between Kieu and her 60-year-old husband over friends staying at their home.
Police say Kieu, who was initially identified as Catherine Kieu Becker, told officers who responded to the 911 call and found her husband tied to the bed and bleeding from the groin that he "deserved it."
Officers have also said she may have drugged or poisoned her husband's food to make him sleepy and that the couple, who married in late 2009, were involved in divorce proceedings.
Kieu's husband was taken to the nearby University of California, Irvine Medical Center following the attack, where he underwent emergency surgery and was listed in serious condition.
Kieu, who is being held without bail, faces a maximum sentence of life in prison without the possibility of parole if convicted.