Payment of the fixed penalty notice within 14 days will reduce the sum to £50, up from the present £30.
And the maximum for repeat offenders will more than triple from £960 to £3,200.
“You must obey the rules on social distancing and to enforce those rules we will increase the fines for the small minority who break them,” the prime minister said on Sunday.
Under the Health Protection Regulations, people can be fined for being outside without “reasonable excuse”.
Pubs, cafes and restaurants can also be penalised for selling food and drink for consumption on the premises.
The same regulation applies to some retail stores if they stay open for customers to make in-store purchases.
Police issued more than 9,000 fines in England and Wales in the first month after the new law came into force on 26 March.
Officials said the penalties were only being used as a “last resort” when people refuse to voluntarily follow the rules.
The changes announced by Boris Johnson apply only to England although the other home nations may choose alter their own regulations in a similar way.