The numbers surpass a previous record set only weeks earlier as migrants took advantage of favourable summer weather.
Britain's domestic Press Association news agency said the figures took annual migrant crossings past 10,000 -- far more than the roughly 8,500 people the government said arrived in the whole of 2020.
The government said they dealt with 21 "events" involving the 482 on Wednesday, while 246 individuals were prevented from reaching southern England by the French.
Dan O'Mahoney, the government's Clandestine Channel Threat Commander, blamed criminal gangs for the situation, and called the situation "unacceptable" and "dangerous".
The growing number of journeys are proving increasingly embarrassing for the government, which has vowed to clamp down on the arrivals and made tightening Britain's borders a key issue in its campaign to leave the European Union.
Last month, home secretary Priti Patel and her French counterpart Gerald Darmanin announced plans to more than double the number of police patrolling French beaches.
Britain also pledged 62.7 million euros ($73.8 million) in 2021-2022 to help France stem the flow of illegal migration.
Patel has promised to make the Channel route "unviable" and proposed legislation to overhaul asylum rules, imposing stricter jail terms for people smugglers and, controversially, migrants themselves.
She maintains the changes -- which have been decried by human rights groups -- are long overdue.
This week Patel met with officials in Greece to discuss cooperation on illegal migration.
During the two-day visit, Patel met ministers in Athens taking part in a patrol with the Greek coastguard to learn more about methods used to prevent small boat crossings.