Rubio's overall message of togetherness and emphasis on the long-standing common heritage with Europe at the annual Munich Security Conference was relatively well received by the gathering of European diplomats and security officials.
But he also echoed the Trump administration's criticism of Europe over issues such as mass migration and climate change and continued to at times needle European policymakers.
Still, his address contrasted sharply with Vice-President JD Vance's address here a year ago, in which he argued the greatest danger to the continent came from censorship and democratic backsliding rather than external threats like Russia.
"In a time of headlines heralding the end of the trans-Atlantic era, let it be known and clear to all that this is neither our goal nor our wish, because for us Americans, our home may be in the western hemisphere, but we will always be a child of Europe," Rubio told the crowd on Saturday.
"For the United States and Europe, we belong together."
With Donald Trump's "America First" agenda increasingly seen as "America Alone", and the president's first 13 months in his second tenure marked by rifts with Europe, Rubio tried to make an appeal to stay united.
"I am here today to make it clear that America is charting a path for a new century of prosperity, and that once again, we want to do it together, with you, our cherished allies and oldest friends," Rubio said.
The address was notably short on specifics. Rubio did not mention Russia - Europe's main geopolitical foil - during the roughly half-hour address, nor did he even bring up NATO by name, the continent's main security bloc or offer an expression of US support for the continent's security.
That Rubio's overall message counted as a relief to European officials speaks to the shifting terrain of trans-Atlantic relations in recent years.
While the vast majority of high-ranking officials and lawmakers in Washington expressed an ironclad economic and military commitment to Europe before the rise of Trump, the current administration had upended that norm.
In the annual US National Security Strategy released in December, Washington warned that Europe faced "civilisational erasure" and might one day lose its status as a reliable ally.
More recently, Trump threatened to slap tariffs on European allies for failing to back him in his quest to wrest Greenland away from Denmark.
"The speech seemed soothing and that is great," one senior European diplomat said.
"There are still many questions looming, but I think using emotional notes was a signal that we can still be together in a different formula."
Other diplomats and US lawmakers were more sceptical, saying the speech had the same undertones as that of Vance.
"It didn't have the fiery tone of Vance, but I think it really got to a lot of the same dynamics, but just again, without really laying out the biggest security challenges that we're facing," Democratic senator Andy Kim told Reuters.
Speeches by European leaders on Friday showed they are increasingly looking to carve an independent path after a year of unprecedented upheaval in trans-Atlantic ties, while also striving to keep their alliance with the US.
German Chancellor Friedrich Merz said Berlin had begun talks with France about a European nuclear deterrent, while President Emmanuel Macron said Europe had to become a geopolitical power given the Russian threat would not disappear.
