On 1 July 2019, anti-government protesters in Hong Kong sieged, broke into, and subsequently occupied the Legislative Council Complex during the campaign to halt the enactment of the Fugitive Offenders amendment bill. Hundreds of protesters broke through the glass walls and metal doors and entered the building, then ransacked and vandalised the interior with anti-government and anti-PRC slogans. The storming is considered a watershed event in the 2019–2020 Hong Kong protests; it was the most violent episode in their initial stage. Nine days later, on 9 July, the Chief Executive, Carrie Lam, announced that the extradition bill was "dead".

On 1 July 2019, as Hong Kong marked the 22nd anniversary of its 1997 handover to China, the annual pro-democracy protest march organised by CHRF claimed a record turnout of 550,000; police placed the estimate at around 190,000, while independent organisations using scientific methods calculated that participation was in the region of 250,000 people. A group of activists splintered off from the peaceful march, and headed towards the Legislative Council Complex. Police estimated that by 9:00 pm, up to 30,000 protesters had gathered around the building.

At around 9:00 pm, hundreds of protesters stormed the legislature after breaking through the glass walls and metal doors of the building. Some estimates put the total number of protesters and reporters in the building at no greater than 300. Police lay in wait while front-line protesters were ramming the main glass door to the building. As the protesters smashed through the secondary gates and entered the building, police initially retreated to avoid confrontation and give the demonstrators the run of the building. Protesters damaged portraits of former pro-Beijing presidents of the Legislative Council, spray-painted slogans such as "It was you who taught me peaceful marches did not work" (是你教我和平遊行是沒用) and "There are no rioters, only tyrannical rule" (没有暴徒祗有暴政), smashed furniture, defaced the Hong Kong emblem, waved the Union Flag and displayed the colonial Hong Kong flag on the podium. At the same time, protesters hung up signs and installed barricades, warning others not to damage books in the library while protesting.

At about 11 pm, occupiers of the legislature were given an ultimatum by the police to leave the building and disperse, or be removed by force. As the evacuation gathered pace, four protesters opted to stay and face arrest but were carried out of the complex by fellow protesters, reflecting the movement's praxis of "Preserve yourself and the collective; no division."

The police started using tear gas to disperse protesters around the Legislative Council complex at 12:05 am, and reached the building 15 minutes later. The government later stated that 15 police officers had been injured in the retaking of the complex.

Protesters broke into the locked Legislative Council building by smashing thick glass doors and prying open metal security curtains. After they had broken through late into the night, they poured into the building and spray-painted slogans on the walls and caused extensive damage. More than 60 glass doors and panes were broken. Protesters vented their anger and frustration at the government for failing to respond to any of their demands. They climbed onto desks in the legislature's main chamber and reached up to spray the official city emblem with black paint, obliterating the portion which read "People's Republic of China", only leaving Hong Kong's part of the emblem untouched, reflecting protesters’ desire to preserve the freedoms, autonomy and judicial independence of Hong Kong, while maintaining its legislature and economic system separate from mainland China. Slogans were also spray-painted on the walls in Chinese and English. "Destroy the Chinese Communist Party," read one. "Hong Kong is not China," said another. One slogan – directed towards Carrie Lam – sprayed in Chinese on a column inside the building read: "It was you who told me peaceful marches did not work" (是你教我和平遊行是没用). Lam had refused to accede to any of the demands despite the massive turnouts at protest marches. Media including CNN and The Guardian noted that the messages protesters sprayed on the wall or displayed using banners, in particular, the phrase "If we burn, you burn with us!" from Suzanne Collins' novel Mockingjay encapsulated protesters' desperation and reflected their pessimism and hardened stance, in stark contrast to the Umbrella Movement.

The fire-prevention and security systems in the chambers were damaged; papers, rubbish, and umbrellas were strewn in lobbies and rooms. Portraits of Andrew Leung, Rita Fan and Jasper Tsang – respectively the incumbent and two former Legislative Council presidents of the SAR era – were defaced, and went missing; parts of wooden picture frames were all that remained of their portraits hung on the wall. The security office and public complaints department were the most heavily damaged: hard disk drives and handheld radios were taken, while security guards said their lockers had been ransacked. Although protesters had destroyed the glass doors of the Legislative Council library, a sign that read “Protect the books, and don't do any damage” was put up; other signs urged protesters to spare the artefacts on display. Protesters paid for drinks they took from the Legislative Council canteen. This was underlined by the sign stuck to the refrigerator, which read, “We’re not thieves, we won't steal.” Protesters blamed the occupation and acts of property damage to be the result of Carrie Lam's "lack of positive response to the public." It was also reported that recent activist suicides had sparked anger and desperation among the protesters, further contributing to the protest on 1 July.

Workers clearing up after the occupation boarded up shattered windows, and police carted away evidence for investigation. Legislative Council president Andrew Leung estimated the cost of repairing the damage by the storming would amount to over HK$40 million.