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.

GB will play Australia, ranked second in the world, in Saturday's final at 13:35 BST.
Sam Ward gave Britain the lead from a penalty corner before Dominic Newman levelled for the Black Sticks.
But strikes from Phil Roper and Mark Gleghorne carried home Bobby Crutchley's side.
Britain's return to the final for the first time since England lifted the trophy in 1994 was confirmed when hosts Malaysia beat India 1-0 later in the day.
"It was a very good performance in stifling heat. I felt we dominated the game," said Crutchley.
"If we had a better conversion rate from the chances we created, the scoreline would have been more comfortable."
Results, fixtures & tables on the tournament's official website

Team Pacific Rowers were taking part in a race between California and Hawaii when their vessel began taking in water about 100 miles from shore.
Rower Sam Collins, 25, from Cornwall, said: "It's really frustrating because we are a great team and it is only the equipment which let us down."
The rowers were airlifted to safety by US coastguards on Saturday.
Mr Collins, Fraser Hart 34, from Tunbridge Wells, James White, 36, from London and Colin Parker, 36, from New Zealand, were taking part in the Great Pacific Race.
The Pacific Rowers team set off on Wednesday to row 2,400 miles (3,862km) from Monterey in California to Honolulu.
Former BBC Guernsey journalist Mr Collins said: "The first couple of days were great. Team spirits were good. We were getting used to life on the boat.
"But the sea conditions were quite rough and worsening.
"Then late in the second day, out at sea, we started realising that water was permeating into the cabin.
"It just got worse and worse."
The crew used an electric bilge pump to keep the problem at bay but the water kept coming in.
Water eventually got into all the internal lockers and the boat was so low in the water that waves were crashing over it continuously, Mr Collins said.
"The boat had been through severe testing but in some places it was permeating through the side of the boat because of the force of the waves," he added.
The team called for assistance and a support boat reached them 10 hours later.
But with waves of 20ft (6m) and gale-force winds, it was decided that the safest rescue was by coastguard helicopter.
In darkness, a helicopter winched the crew to safety.
"I cannot talk highly enough about the coastguards," he said.
The team is now considering entering the 2016 event.
"We are very disappointed, a lot of effort went into this," said Mr Collins.
Irish Taoiseach (PM) Leo Varadkar has engaged in some "sock diplomacy" in his first meeting with Canadian Prime Minister Justin Trudeau in Dublin.
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Great Britain claimed a 3-2 win against New Zealand in the Sultan Azlan Shah Cup to become the first British side to reach the final in 23 years.
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One of four rowers rescued from the Pacific said extreme weather conditions had exposed weaknesses in their boat.