New figures for England and Wales brought the death toll to at least 42,990, a Reuters tally showed, including earlier data from Scotland and Northern Ireland, as well recent hospital deaths in England.
Tuesday's numbers from the Office for National Statistics painted a grim picture in care homes, more than a third of which have been stricken by the novel coronavirus.
Deaths in care homes across the United Kingdom topped 10,000 as of May 8, although the increase has slowed over the last couple of weeks.
Comparisons with other countries are tricky, but the data confirmed Britain was among those hit worst by the pandemic , which has killed more than 317,000 worldwide.
Such a high UK death toll increases the pressure on Johnson, who says the government is following scientific advice. Opposition parties say he was slow to introduce testing and provide protective equipment to health workers, and that his policy left care homes exposed.
In March, Britain's chief scientific adviser said keeping deaths below 20,000 would be a "good outcome." In April, Reuters reported the government's worst-case scenario was 50,000 deaths.
Unlike the daily death toll announced by the government, Tuesday's ONS figures include suspected deaths from COVID-19.
Ministers dislike international comparisons of the death toll because Britain's performance reflects its fast reporting of COVID-19 deaths data.
They say excess mortality - deaths from all causes that exceed the seasonal average - is more meaningful because it is internationally comparable. But Britain is faring poorly on this measure, too.Excess deaths across the UK are now close to 55,000, ONS statistician Nick Stripe told the BBC.