Pictures of the huge sea of people who marched for hours on Sunday in sweltering heat were splashed across Monday's newspaper front-pages, as editorial writers spelt out the challenge for Leung on his first day in office.
"Leung Chun-ying becomes a lame duck," the Chinese-language Apple Daily News, which is known for its anti-Beijing views, blared in a banner headline.
Even before his term began, Leung had already attracted protests drawing thousands of people decrying Chinese interference in the March election where he was picked by a committee stacked with pro-Beijing elites.
Political analysts say that while it is premature to write Leung off already, he has to navigate a particularly rocky road.
"Usually we expect a newcomer to have a sort of honeymoon period but he will never have one, it will be a difficult period for him," Chinese University of Hong Kong political analyst Ma Ngok told AFP.
"He didn't start with high popularity even when he was so-called elected," he said. "His popularity rating hovered around for a while and it nose-dived after the recent scandals."
Just a week before his inauguration, Leung was forced to apologise over illegal improvements at his luxury home and faced criticism from an inquiry into a conflict-of-interest row involving a government project a decade ago.
A poll released by the University of Hong Kong last week showed Leung's popularity rating falling to 51.5, down 4.2 points from a month ago, with nearly 40 per cent of people saying they did not trust the government.
"If he wants to give Hong Kong people a chance (to trust him), he should show himself to be fighting for democracy and not just kowtowing to Beijing," leading pro-democracy lawmaker Lee Cheuk-yan said.
The 57-year-old Leung urged people to work with him Monday, as he gears up to lead the city into its first direct election at the end of his five-year term.
Hong Kong does not get to choose its leader via universal suffrage yet. But Beijing has promised a direct election for the chief executive post in 2017, and for the legislature by 2020.
"Hong Kong doesn't belong to just a small group of people, it belongs to everyone, so I hope everyone can be a part of it," said Leung, who dressed down in an orange T-shirt as he met locals in a town hall-style meeting.