"The whole world benefits from a strong EU," he said in a speech to the European Parliament, a day after MEPs approved a landmark free trade deal between the EU and Canada.
"Canada knows that an effective European voice on the global stage isn't just preferable, it's essential," Trudeau told the assembly in Strasbourg, France.
Trudeau also hailed the 28-nation bloc as "a truly remarkable achievement and an unprecedented model for peaceful cooperation."
The European Parliament on Wednesday solidly backed an EU-Canada trade accord after nearly eight years of painful negotiations and activist anger.
Opponents to the deal, known as CETA, slam the deal as a "Trojan horse" to big business and a danger to health, democracy and the rule of law.
Trudeau, speaking in a mix of French and English, said that the EU and Canada "have made a big step to deepen our relationship and increase commerce that is both free and progressive".
Trudeau spoke three days after meeting in Washington with US President Trump, who has vowed to embrace protectionism and reject big trade deals in order to preserve US jobs.
"The conversations I had in Washington and the conversations I had here in Strasbourg are anchored in exactly the same thing -- a recognition that governments need to do better at creating growth and opportunities for all our citizens," Trudeau told reporters after his speech.