Ten London postcodes qualified for admission - which requires at least a fifth of homes to sell above the six-figure threshold price in two or more three-month periods since the second quarter of 2020.
Outside the capital, new £1 million markets include North and West Oxford (OX2), Tunbridge Wells (TN3) and Reading (RG8).
Researchers said analysis of Land Registry data suggests that the pandemic has not upended the UK housing market: instead, as the stamp duty holiday winds down and the impact of Covid fades, property prices have undergone a "subtle rather than transformative change".
Knight Frank said the latest figures underline the growing demand for space and greenery following successive lockdowns with the creation of new £1 million property markets rippling beyond central London and leapfrogging inner suburbs.
“The pandemic has left its mark on the UK property market by magnifying existing trends rather than re-writing the rulebook,” said Tom Bill, its head of UK residential research.
“Things won’t pick up from where they left off in March 2020 but the wider trajectory will feel familiar.”
On a local level, Newquay in Cornwall saw the largest house price increase (+22%) in the year to March 2021, followed by Ryde on the Isle of Wight (+19%).
The top five, which is based on repeat sales data, is completed by Chapeltown in Leeds (+19%), Lymington in the New Forest (+18%), and St Austell in Cornwall (+17%).
The “space race” for bigger gardens has also narrowed the gap between the capital and the rest of England and Wales.
The average house price in England and Wales was 47% of the London equivalent in March 2016, the lowest ratio since Land Registry records began in 1995.
It has been rising since and stood at 54% in June this year due to stronger demand and price growth outside of the capital.
The gap is likely to narrow further.
Average London prices in June this year were 71% above their pre-global financial crisis peak in November 2007. For the whole of England and Wales, the figure was 46%, showing the greater scope for future growth.
The researchers said the return of international buyers will temper this and expect price growth in prime central London to outperform the rest of the country in 2022.
It said: "The direction of travel is clear. Covid has left its imprint on the UK property market but there will also be something quite recognisable about what comes next."