The New Zealand prime minister shared a 90-minute conversation with the US president on Wednesday (AEDT) at the end of Ms Ardern's 10-day visit to the United States.
The pair talked regional security in the Pacific, Russia's invasion of Ukraine, multilateral trade and gun law reform.
The congenial 79-year-old host was effusive in his praise for Ms Ardern, citing her efforts on climate change and tackling online radicalisation, two other topics of discussion.
"You understand that your leadership has taken on a critical role on the global stage?" he asked Ms Ardern.
Under Mr Biden's leadership, the US has signed up to Ms Ardern's flagship foreign policy: the Christchurch Call.
The Call is a multilateral forum which brings together tech companies and countries to combat online extremism, forged in the wake of the 2019 Christchurch Mosques terror attack.
Mr Biden invoked the latest school massacre in his country, in Uvalde, Texas, last week, when discussing the importance of ending gun violence.
"There's an expression by an Irish poet that says, 'too long of suffering makes a stone of the heart'. Well there's an awful lot of suffering," he said.
"The work you're doing with tech companies is really important ... and I want to work with you on that effort."
On trade, New Zealand was left disappointed - as expected - by the US's unwillingness to enter free trade talks or to enter the CPTPP, the Pacific-wide framework which it left during Donald Trump's administration.
"With regard to discussions on CPTPP, I think the Prime Minister has made her views very clear," a White House official said.
Speaking outside the White House, Ms Ardern said New Zealand would instead engage through the Indo-Pacific Economic Framework (IPEF), a 14-nation framework created last month by Mr Biden.
"We as a nation are very focused on making sure that we see tangible deliverables from that opportunity which has been presented," she said.
Given the alarm bells that sounded when the Solomon Islands announced a security tie-up with China in March, regional security in the Pacific was also at the fore.
"We are not coming to dictate or lay down the law ... we have more work to do in those Pacific islands," Mr Biden admitted.
Ms Ardern said the meeting was warm and friendly and she was "greatly heartened" by Mr Biden's engagement.
The Kiwi PM was asked whether she invited Mr Biden and Vice President Kamala Harris, who she met earlier in the day, to New Zealand.
"You know me. Of course I did!" Ms Ardern exclaimed.
The Kiwi PM announced the trip without a confirmed audience with Mr Biden, a matter which was complicated by her bout of COVID-19 last month.
She will return to Wellington on Thursday.
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