The survey by WealthInsight found that Windsor had 850-900 millionaires, those with over £650,000 in net assets excluding property. The sum equates to approximately US$1m, an international measure of wealth status.
In second and third place were Weybridge in Surrey and Sevenoaks in Kent, both with 800-850 millionaires each.
Eight of the 10 locations on the table were in the South East of England with only Hale and Alderley Edge from the rest of the UK.
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The remaining towns on the list were Beaconsfield, Henley on Thames, Marlow, Bray and Ascot.
However, the number of millionaires overall declined by nine per cent.
WealthInsight's Andrew Amolis said: "Towns in the London commuter belt dominate the top 10 although it is interesting to see that a couple of towns around Manchester also make the list. This reflects the affluent nature of the Cheshire area.
"Henley on Thames is the fastest growing town on the list with millionaire numbers there rising by 25 per cent over the period between 2007-2012."
Towns which narrowly missed out on the top 10 were Windermere in Cumbria, Pangbourne in Berkshire, Dartmouth in Devon and Burford in the Cotswolds. These all had 200 millionaires each.
The survey follows research last week which showed that London was the top city in the world for multi-millionaires, ahead of Moscow and New York City. It was also in the top three for millionaires and billionaires.