Foreign Secretary James Cleverly has revealed that the UK's Ukraine Cyber Programme was launched shortly after Putin's invasion in February to protect against increased Russian cyber-attacks.
However, the programme had been kept quiet until now in order to protect its operational security.
The programme has been used to provide incident response support to infrastructure run by the Ukraine government and prevent malicious actors from accessing vital information relevant to the war effort.
Ukraine has had a long history of facing cyber-attacks on its critical infrastructure from Russia – despite the country repeatedly denying its involvement.
Especially since the Russian invasion of Crimea in 2014, Ukraine has been forced to reckon with repeated attacks on its telecommunication systems, power grid and airports.
In January, during the prelude to this year's attempted land invasion of Ukraine, Russia stepped up its hacking efforts once again targeting government websites and bank services. Independent hacker groups, such as Anonymous, have since launched cyberattacks on Russia in retaliation for the invasion.
The UK's latest package has limited attacker access to vital networks, the Foreign Office said, and has hardened their critical infrastructure against future attacks.
It has also delivered frontline cyber-security hardware and software including firewalls to prevent attacks taking hold, DDoS protection to ensure Ukrainian citizens can continue to access vital information and forensic capabilities to enable Ukrainian analysts to fully understand system compromises.
"Russia's attack on Ukraine is not limited to its horrific land invasion. It has also persistently attempted to invade Ukraine's cyber space, threatening critical information, services and infrastructure," Cleverly said.
"The UK's support to Ukraine is not limited to military aid: we are drawing on Britain's world-leading expertise to support Ukraine's cyber defences. Together, we will ensure that the Kremlin is defeated in every sphere: on land, in the air and in cyber space."
Lindy Cameron, CEO of the National Cyber Security Centre, said: "[Ukraine has] mounted an impressive defence against Russian aggression in cyber space, just as they have done on the physical battlefield.
"The threat remains real and the UK's support package is undoubtedly bolstering Ukraine's defences further."
In September, the United Nations made efforts to ensure some level of cooperation between Russia and Ukraine in order to establish a nuclear safety and security protection zone around the Zaporizhzhia nuclear power plant.