A new deal will see British warships and missiles sold to Ukraine, amid concerns over rising tensions with Russia.
Defence Secretary Ben Wallace signed a treaty with Ukraine last week which will see the country access financing for contracts with UK suppliers to beef up its naval capabilities.
The deal is expected to help Ukraine get two mine counter-measures vessels (MCMV), the joint production of eight missile ships and the delivery of and retrofit of weapons systems to existing vessels.
It is also expected the deal will deliver the joint production of a frigate and consultancy and technical support for the building of naval infrastructure including the delivery of equipment.
In a joint statement, Mr Wallace and Ukraine Defence Minister Oleksii Yuriyovych Reznikov said the two governments "have no desire to be adversarial, or seek in any way to strategically encircle or undermine the Russian Federation".
Watch: NATO chief calls on Russia for transparency on military activity near Ukrainian borders.
"We are concerned by Russia's military build-up and activity around the borders of Ukraine," the statement said.
"Ukraine’s national sovereignty and territorial integrity is indisputable.
"The United Kingdom stands shoulder to shoulder with the people of Ukraine and will continue its long-standing determination to support them.
"We are unwavering in that support and together we remain vigilant and united in the defence of our common values and freedoms.
It comes after Boris Johnson warned Vladimir Putin against making a "tragic mistake" as tensions rise on the border between Russia and Ukraine.
The Prime Minister, appearing at the Commons Liaison Committee, was asked about the problems between Belarus and Poland and the situation in Ukraine.
Thousands of migrants, mainly from the Middle East, have been amassing at the Belarus border with Poland for months.
Watch: Why are UK troops being sent to the Polish border?
Brussels has accused Belarus' authoritarian president Alexander Lukashenko, a close ally of Russian President Vladimir Putin, of deliberately encouraging the migrants to breach its borders in retaliation for sanctions the European Union has imposed in response to his repressive rule.
But reports on Wednesday suggested that hundreds had been moved to a nearby warehouse in Belarusian territory.
Downing Street has also voiced concern about the build-up of Russian forces on Russia's border with Ukraine.
The Kremlin has dismissed claims that it is preparing to invade, after the Ukrainian defence ministry reported that around 90,000 Russian troops were massing in the area.
Mr Johnson said the two cases are "very different" because Poland has a NATO security guarantee, meaning that any action against it could trigger a response from the entire alliance.
Ukraine does not have the same guarantee, "so what we have got to do is make sure that everybody understands the cost of a miscalculation on the borders of both Ukraine and Poland would be enormous".