The benchmark FTSE 100 index jumped 1.83 per cent to stand at 7,013.0 points in midday deals, lifted by soaring share price gains for banks and energy majors.
Among the biggest winners were energy firm Centrica, up 7.50 per cent to 276.70 pence and state-rescued Lloyds Banking Group, up 6.56 per cent to 87.53 pence, with the Conservatives seen as being less tough on regulating the financial and energy sectors compared with the Labour party, which will stay as the main opposition party.
As the results rolled in, forecasts of a close contest between the Conservatives and Labour turned out to be wide of the mark, with Cameron on course to win a majority in parliament and secure five more years in Downing Street.
The outcome sent the British pound soaring to USD 1.5423 from USD 1.5262 late in New York on Thursday. The euro was down at 72.71 pence from 73.82 pence.
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"A night of victory for the Conservative party has put UK markets on the front foot, with sterling and the FTSE moving higher," said Chris Beauchamp, senior market analyst at IG trading group.
"For investors, the results... Mean that they can cease worrying about the UK economy, and focus on the other areas of concern, like Greece and whether the Fed will hike rates this year."
"The result removes the risk that the economy suffers a prolonged period of political uncertainty," said Vicky Redwood, chief UK economist at Capital Economics research group.
The success of the SNP could increase pressure for a fresh referendum on Scottish independence, even though that was rejected just last September.
An overall victory for the Conservatives will meanwhile trigger a referendum on Britain's membership in the EU by 2017.