But Family First MLC Dennis Hood said the bill was "dangerous" and he was relieved it was defeated.
"Parliament has spoken loud and clear. Voluntary euthanasia for SA has been soundly defeated and should be moved off the agenda," he said.
"I am grateful that members listened to my concerns and made the decision on conscience to oppose the bill."
Mr Hood said the bill would have allowed euthanasia for patients that did not have a terminal illness, left psychological referral of patients as an option only and offered a "toothless" Voluntary Euthanasia Board to oversee the practice.
In September this year, Ms Key announced she would introduce the bill into parliament's lower house while Greens upper house MP Mark Parnell will put the identical bill to the Legislative Council.
Mr Parnell had similar legislation defeated in the upper house last year.
At the time, Ms Key said it was time for the SA parliament to catch up with public opinion.
"Over 80 per cent of Australians support the right of the terminally ill and others living in intolerable pain and suffering to seek the assistance of a doctor to end their own lives at a time and in the circumstances of their choosing," she said.
Mr Parnell said the bill required a patient to be examined by two doctors, including at least one specialist and oversight by a Voluntary euthanasia Board.
But influential Port Pirie Catholic bishop Gregory O'Kelly was among vocal opponents of the plan, blaming the recent rise of minor political parties for "pushing death.
"It is a sadness that the first moves around our nation under our new political arrangement seem to be a promotion of death and abuse of marriage," he said in September.