"Kuwait's killing of seven people on January 25 highlights the alarming trend in the region for countries to return to or increasingly use the death penalty," said Sarah Leah Whitson, HRW's Middle East director.
The executions on Wednesday were the first in Kuwait since mid-2013 when five people were hanged in two months following an earlier moratorium of six years.
Those executed this week were two Kuwaitis and five foreigners -- two Egyptian men, a Bangladeshi man, a woman from the Philippines and a woman from Ethiopia.
Six of those hanged on Wednesday were convicted of murder, including a member of the ruling family and a woman who burned dozens of people to death at a wedding party.
"Executing seven people in one day shows Kuwait is moving in exactly the wrong direction on the death penalty," Whitson said.
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"The Kuwait government should be reinstating the moratorium on the death penalty instead of hanging seven people," she said.
HRW said use of the death penalty was on the rise across the Middle East.
Earlier this month, Bahrain ended a six-year de facto moratorium on the death penalty, executing three people.
Jordan in December 2014 executed 11 people for the first time in eight years.
Saudi Arabia and Iran consistently have some of the world's highest execution rates, HRW said.
Since the beginning of 2014, Saudi Arabia has executed more than 400 people, and human rights groups in Iran report the country may have executed as many as 437 last year alone.
Amnesty International also condemned the Kuwaiti executions as "shocking and deeply regrettable."