The UK and Sweden have signed a letter of intent that will see 14 Swedish-built Archer self-propelled guns delivered to the British Army.
The purchase of the Archers enables the UK to support Ukraine by donating AS90 self-propelled guns.
The visit on Wednesday also saw the UK commit to supporting Sweden's swift accession to Nato.
The two countries' defence ministers met in the UK and, as well as the Archer deal, discussed potential future collaboration.
Defence Secretary Ben Wallace said Sweden has "provided vital military aid and integral support" to both Ukraine and Nato allies through the Joint Expeditionary Force (JEF).
JEF drives the defence relationship between the two countries, as well as the May 2022 UK-Sweden Mutual Solidarity Agreement – driving intelligence-sharing and joint training.
"The UK will continue to give our full support to Sweden's accession to Nato, fortifying Northern Europe and the Baltics against Russian aggression and expanding security challenges in the region," Mr Wallace said.
Both JEF and the UK-Sweden Mutual Solidarity Agreement have been supported by joint exercising of Royal Air Force Typhoon aircraft and the Swedish Air Force, as well as by visits from Royal Navy vessels.
Sweden's defence minister Pål Jonson said the Archer deal will see the strengthening of relations between the two countries.
"The British leadership, when it comes to supporting Ukraine, is an inspiration for all of us and both Sweden and the UK will continue to support Ukraine until victory is achieved," he said.
"I thank the UK for the quick ratification and the support of our Nato membership application.
"The UK has shown continued political support but also military presence in our neighbourhood – both bilaterally and through the JEF – which is pivotal to our security during the accession period."
This spring will see the British Army join the Royal Navy and RAF for Exercise Aurora – with British personnel joining Finnish and Swedish troops in Sweden.
Swedish industry has also helped the UK support Ukraine through the donation of Nlaw anti-tank weapons.