Since the last executioner retired in 2005, 76 prisoners have been held on Death Row. Prison officials last week said only that the search for a hangman was over and did not elaborate.
Some convicts were condemned to death 12 years ago and rights groups have campaigned for all the death sentences to be commuted to life, describing years of delays as inhumane.
Amnesty said in a statement the "macabre recruitment" was a disturbing sign that bucked against world trends to abolish the death penalty.
After touring the main Harare prisons on February 1, state media reported that the hangman signed on "mid last year" but has yet to be put to work.
Noel Kututwa, Amnesty International's southern Africa director, said Friday Zimbabwe is a signatory to international human rights protocols that recognise the death penalty is "the ultimate denial" of the right to life.
"It is the premeditated and cold-blooded killing of a human being by the state," he said.
A new constitution proposed ahead of national elections in Zimbabwe later this year exempts women and offenders younger than 17 and older than 70 from execution.
Of the 76 prisoners now on Death Row, just two are women and the exclusion of women "would therefore not significantly reduce the use of the death penalty," Kututwa said.
The proposed constitution also calls for the death sentence to be imposed only in cases where extreme and aggravated violence is used by offenders.
"We oppose the death penalty in all cases without exception, regardless of the nature of the crime, the characteristics of the offender or the method used by the state to kill the prisoner," Kututwa said.
During the seven years, Zimbabwe's prison service prepared advertisements looking for a hangman. The former executioner was said to have taken retirement after struggling with his conscience. His identity was never revealed.
Officials said they received replies to the wanted ad from as far afield as Malaysia. One applicant was reported to have been from the southern African country of Malawi. The officials said ancient Zimbabwean culture, tradition and superstition on death and deep beliefs in the tribal spirit world deterred local applicants.
A group that campaigns against capital punishment said the job ad specified that a high school education was required but made no mention of execution by hanging needing knowledge of human physiology and basic mechanics.
Records show that nearly 100 convicts have been executed in Zimbabwe since the country won independence from Britain in 1980.
Hangings were suspended for a decade after President Robert Mugabe met with Pope John Paul II in Harare 1988. During the moratorium, scores of inmates' death sentences were commuted to jail terms on humanitarian grounds and several have since been released. – Sapa-AP