In a nod to Mr Trudeau's fondness for statement socks, he wore Canada-themed mountie and maple leaf print ones to welcome his first foreign visitor.
Mr Trudeau opted for a more subtle striped pair on his first official engagement in the Republic of Ireland.
The Canadian premier is in the country for a three-day visit.
Away from talk of socks, trade issues are set to dominate the agenda, with the Canada-EU free trade deal expected to be a focal point of talks between the two leaders.
Mr Trudeau arrived in Dublin with his wife, Sophie GrÃ©goire, and their youngest son, Hadrien, on Monday.
He is in Europe for a key G20 summit in Hamburg, Germany later this week.
Mr Trudeau is also due to meet Irish President Michael D Higgins at his official residence.
The visit was arranged in May when Mr Varadkar's predecessor Enda Kenny met the Canadian leader in Montreal.
On that occasion, Mr Trudeau wore special Star Wars themed socks, as it coincided with the widely-celebrated Star Wars Day on 4 May.
Irish Taoiseach (PM) Leo Varadkar has engaged in some "sock diplomacy" in his first meeting with Canadian Prime Minister Justin Trudeau in Dublin.