A poll carried out by YouGov found that 55% of Britons now hold a favourable opinion of the prime minister, compared to just 33% when he took office in December.
By contrast, only 35% of people now hold an unfavourable opinion of Mr Johnson, leaving him with a net score of +20 – his highest rating by some distance since becoming leader.
YouGov data shows that most of the new support comes from voters who didn’t back the Conservatives in 2019.
Last week, only one in 10 Labour voters had a favourable view of Johnson, and now it’s a quarter.
Similarly, amongst Lib Dems, 38% now have a positive opinion of him, up from 18% over the same period.
It comes after Mr Johnson announced a series of sweeping draconian measures which will be in place for at least three weeks and will also see the closure of libraries, playgrounds and outdoor gyms, and places of worship.
Latest coronavirus news, updates and advice
He also threatened police fines for anyone who ignores new measures including a ban on public gatherings of more than two people.
Mr Johnson ordered people to only leave the house to shop for basic necessities “as infrequently as possible” and to perform one form of exercise a day.
The prime minister has previously faced criticism from figures such as former health secretary Jeremy Hunt who said earlier this month that the government’s delay in imposing a lockdown was “concerning”.
Former Conservative leadership candidate Rory Stewart has also previously criticised Mr Johnson for “just not taking this seriously”.
On Monday night, however, politicians across the spectrum, including those who had been highly-critical of the PM’s response so far, welcomed the tough new measures.
Labour leader Jeremy Corbyn said it was the “right response”, but called for clearer guidance.
“There now needs to be clear guidance to employers and workers about which workplaces should close – and the Government must close the loopholes to give security to all workers, including the self-employed, as well as renters and mortgage holders,” he said.