Mo Farah successfully defended his Olympic 5,000m title in Rio as Great Britain won 66 medals to surpass their medal haul from London 2012.
Farah’s victory added to his gold in the 10,000m as he repeated the distance double he won four years ago.
His medal was GB’s 65th before bronze for the women in the 4x400m relay took Britain past the haul from London.
Wins for Nicola Adams and Liam Heath helped take GB’s gold tally to 27 as they won six medals in all on Saturday.
Adams successfully defended her flyweight boxing title, while Heath won the kayak single 200m sprint on the penultimate day in Rio.
Farah, 33, is now the world’s most successful distance runner in terms of major medals, with nine Olympic and world titles.
The final medal total will be at least 67, with boxer Joe Joyce guaranteed a gold or silver in Sunday’s super-heavyweight final.
Day-by-day guide: What to look out for
This was already Team GB’s most successful overseas Olympics – eclipsing the 47 medals won in Beijing in 2008 – and is the best medal return at any Games since the 146 amassed in London in 1908.
It is also the first time since the modern Olympic era began in 1896 that a country has increased its medal tally at the summer Games immediately following one it hosted.
Vicky Holland and Bianca Walkden were the other GB medallists on day 15.
Holland won bronze in the women’s triathlon, while taekwondo fighter Walkden took bronze in the +67kg category.