Ms May says that she used her 20-minute meeting with the prince to urge him to work with the United Nations to find a solution to the long-running conflict in Yemen.
And she also called for an “open and transparent” legal process in relation to the murder of the journalist Jamal Khashoggi.
But Mr Corbyn said the PM was not going far enough in signalling the UK’s disapproval of the actions of Saudi Arabia’s de facto ruler.
“She should confirm the UK government will immediately stop selling arms to his regime and hold him to account over the horrific murder of the journalist Jamal Khashoggi,” said the Labour leader.
“The UK has pumped £4.6bn worth of military equipment into the conflict in the Yemen. Almost a quarter of a million people will have been killed by the end of this year – more than half of them under five years old.
“The Court of Appeal has found the UK government ‘made no attempt’ to conclude whether the Saudi-led coalition had committed violations of international humanitarian law in the Yemen.
“Where the UN sees ‘humanity’s biggest preventable disaster’, this Conservative government sees an arms sales opportunity.
“It is simply not good enough for Theresa May and her government to take the Saudis at their word.
“The evidence that war crimes have been committed in the Yemen, the indiscriminate attacks on civilians, the horror of mass killing and starvation, and the brutal murder of opponents at home and abroad, should mean Saudi Arabia should be held to account, not embraced as military allies.”
The crown prince has become the focus of international condemnation since taking the helm in Riyadh in 2017, due to his bombing of neighbouring Yemen and alleged links to the Khashoggi killing.
Four years of the Saudi-led bombing campaign designed to oust the Houthi rebels who hold much of Yemen have led to more than 8,000 civilian deaths and 9,500 injuries, according to the independent monitoring group Yemen Data Project. And tens of thousands more have died as a result of the fighting and disruption to food and medical supplies.
A United Nations-led peace process was threatened by allegations from the Saudi-backed official Yemeni government that the UN special envoy Martin Griffiths was siding with the rebels.
The UK government is appealing against a court ruling that arms sales to the kingdom were unlawful because of the likelihood that weapons would be used in breaches of international humanitarian law in Yemen.
Meanwhile, a trial of 11 individuals at the Riyadh Criminal Court in relation to the Khashoggi murder has been taking place behind closed doors and the defendants – five of them facing the death penalty – have not been named.
A UN report found there was “credible evidence” that the prince and senior officials were individually liable for Khashoggi’s death at the Saudi consulate in Istanbul last October.
But Riyadh insists it was the result of a “rogue operation” by agents who were intended to return him to Saudi Arabia.
Speaking after the meeting in Osaka, a senior British official said: “The prime minister reiterated the need to keep working on finding a solution to the current conflict in Yemen, which is causing significant humanitarian suffering, and the importance of continuing to make progress through the UN peace process.
“On accountability for the murder of Jamal Khashoggi, the prime minister said the legal process needed to be open and transparent.”
Speaking ahead of the meeting, Ms May defended her decision to sit down with world leaders like the prince and the Turkish president Recep Tayyip Erdogan, who has faced criticism for his heavy-handed response to the 2016 attempted coup in his country.
“These are all individuals sitting around the G20 table,” she said. “The G20 is about that international cooperation.
“I will be promoting that international rules-based order, I will be promoting that international cooperation and I will be giving that message to those that I meet individually and collectively around the G20 table.”