The bloc was dealing with "an openly hostile world", Ursula von der Leyen said in her annual speech to the European Parliament in Strasbourg, France, setting out priorities for the 27-nation EU for the year ahead.
Solidarity among member states was the only possible solution, she said on Wednesday.
"Our path is clear: building an independent Europe that has the power to act."
The 27-nation bloc faces war at its borders, with Russia's invasion of Ukraine.
On trade and other issues, it is also facing stiff rivalry from Donald Trump's United States and from an increasingly assertive China.
The EU faces major headwinds at home as well, including the increasing popularity of a eurosceptic far right, seen in regional elections in Germany that have weakened Chancellor Friedrich Merz.
Opinion polls see Marine Le Pen as the strongest contender in 2027's presidential vote in France.
"The state of our Union is the strongest it has ever been. The state of our Union can also feel as precarious as it has ever been," von der Leyen said.
Von der Leyen, now in her second five-year term at the helm of the EU executive arm, was also set to stress the need to maintain European independence in various sectors, including energy, raw materials and clean technologies.
To achieve that, EU countries will not only need to work together, but also have strong partners like Canada, whose Prime Minister Mark Carney is in Strasbourg and was warmly applauded by EU MPs as he arrived to listen to von der Leyen's speech.
"We want to bring the relationship with Canada to the highest level possible," von der Leyen said.
"So, I would like to work with you on opening the door for Canada to be the first associate member of the EU."
Von der Leyen walked up to and embraced Carney after mentioning the "associate membership" issue for Canada and Carney got a standing ovation from the chamber.
The overture comes as Trump's tariffs and repeated talk of making Canada the 51st state have pushed Ottawa to seek closer economic and security ties with Europe.
Carney has called for a "unique alliance" with the EU as Canada seeks to reduce its heavy dependence on US trade.
He is due to address the European Parliament on Thursday.
Von der Leyen said Canada and the EU would build on their existing free trade agreement, known as CETA, with a broader "Alliance for the Future" aimed at creating "a common prosperity and economic security space".
She cast that closer relationship as rooted not just in trade but in shared democratic values.
Turning to trade, von der Leyen said the EU will use every possible means to reduce its "unsustainable" trade deficit with China.
She said that the imbalance, with a goods trade deficit of one billion euros ($A1.6 billion) a day in 2025, had reached a tipping point.
"Let me be clear: we will use all the tools at our disposal to rebalance our relationship. Words are good. But deeds are better," she said.
Von der Leyen also said the bloc will need to stay its ambitious course on mitigating climate change but also step up efforts to adapt to it, drawing on experiences from the past three months when the continent was hit by unprecedented heat waves and wildfires.
with AP
