The embattled eastern European country has been added to Canada's automatic firearms country control list.
The decision was made on Nov. 23, according to a cabinet order posted online.
It was released publicly on Wednesday, as the House of Commons prepared to rise for the Christmas break.
The long-standing plea by the Ukrainian government was a feature of last fall's meeting between President Petro Poroshenko and Prime Minister Justin Trudeau.
The move puts Canada out ahead of the United States, which has been considering its own weapons sales.
In a statement, Foreign Affairs Minister Chrystia Freeland said the decision reflects closer ties between Canada and Ukraine.
It is, however, expected to anger both the human rights groups that petitioned against it and Russia, which annexed Crimea in 2014 and has been accused of supporting separatist forces in eastern Ukraine.
Conservative defence critic James Bezan said he welcomed the move and noted the process was started under the previous Conservative government.
The fact that it took two years, from the time the Stephen Harper government initiated the review to the cabinet decision last month, is inconceivable, he said.
"It should have gone much quicker," Bezan said.
There are 39 countries on the control list and the announcement — in the federal government's official publication — noted that the federal cabinet still maintains control over the process.
Contractors who strike a deal with Ukraine will have to apply for an export permit, which "must be assessed on a case-by-case basis," said the Canada Gazette posting.
Each sale must include a so-called end-user and end-use assessment, which spells out who gets the weapons, how they will be employed and that they won't be used against civilians.
Ukraine applauds decision
It is a significant decision and important signal to the international community, said Oleksil Makeiev, the political director of Ukraine's foreign ministry.
"It's a very practical thing that Ukraine would be able to get — or to buy — firearms which we badly need to defend ourselves," Makeiev said in an exclusive interview with CBC News during a visit to Ottawa this week.
"While we reform our armed forces and we achieved a lot on this path in the last year, we need also to arm our guys and to make further aggressive actions of Russia and Russia-supported gangs in [the east] harder. We defend our territory."
"This is a very strong signal to the Russian Federation from Canada," Makeiev added.
Ukraine has insisted the weapons it intends to buy are "defensive" in nature, but human rights groups don't buy that argument.
Both Project Ploughshare and Amnesty International Canada opposed the plan in a written submission to Global Affairs Canada, saying the human rights situation in the country needs to improve. As evidence they pointed to the tactics used by police under former president Viktor Yanukovych to crackdown on protests in 2013 and 2014.
Washington has been considering weapons sales to Ukraine and a plan — according to multiple published reports in the U.S. — has been sitting on President Donald Trump's desk for weeks unsigned.
There has been speculation in the U.S. media that Trump is loath to annoy Russian President Vladimir Putin.
Canada is setting a "very good example in terms of the ongoing discussions in the United States, in some European countries," demonstrating that, "Ukraine shall be supported," said Makeiev.
The U.S. special representative to Ukraine, Kurt Volker, recently told Politico there's no reason, in his estimation, to continue the prohibition on lethal weapons sales.
"The U.S. has defence relationships and arms sales relationships with dozens and dozens and dozens of countries around the world," he told the U.S. online publication on Nov. 27.
"And there isn't anything compelling that I can see as to why Ukraine should be a special case, why we wouldn't do that, especially when they're actively trying to defend their territory."
Canada and the U.S. have, thus far, only delivered non-lethal aid to the country which has been battling Russian-backed secessionists in two eastern districts since 2014.
Ukraine already has a robust arms industry, ranking 77th among the top 100 weapons-makers in the world, according the Stockholm International Peace Research Institute.
The country has long been interested in more sophisticated Western technology, equipment such as anti-tank weapons, counter-battery artillery radar, and armoured patrol vehicles like the U.S.-made Humvees.
By Murray Brewster, CBC News