Anders Ygeman holds the position of interior minister in Sweden, the equivalent of May's current home secretary role in the UK.
In a statement provided to The Local, he highlighted the close work she has done in the past with the Nordic nation in the EU.
“The United Kingdom and Theresa May as its home secretary have been a good and close partner for us in the EU,” Ygeman said.
“Together we have tackled questions on terrorism and the restriction of illegal weapons.”
Britain's decision to leave the EU means Sweden will lose one of its closest allies in the union, with a recent independent survey showing that the two countries voted the same way in almost 89 percent of votes on European policies.
And Swedish minister Ygeman pointed out the difficulty of the European task that now awaits May in her new job as British leader.
“May now has a big and difficult challenge in how the UK’s withdrawal from the EU will go, and what kind of relationship the UK should have with the EU in the future.”
May will be officially sworn in as Prime Minister on Wednesday after David Cameron formally resigns on the same day.