He accused the main parties of "deceiving" the public over Europe and said withdrawing from the EU would save the UK billions of pounds, describing the move as his "top priority".
"With the Lisbon Treaty, you really see the last nail in the coffin of our democracy," he said. "The EU can do almost anything and will."
The party's objective at the next election - in which it plans to field more than 500 candidates - would be to force a hung Parliament and bring about a "realignment" in British politics.
He said the party would still be "majoring on leaving Europe" - but he also pledged to campaign on a range of other issues including Swiss-style direct democracy, which he described as a "serious system of national and local referendums".
"I am convinced that is the only way now that the people can get round the stranglehold of their political class and take back their democracy."
He said the party's first referendum was likely to be on EU withdrawal but he envisaged plebiscites taking place on other issues when sufficient members of the public wanted them.
He promised policies "in all areas", notably tightening border controls, reforming the training of teachers and nurses, building more grammar schools and preventing the closure of post offices.
He also pledged to improve the party's organisational structure, modernising its campaigning and fundraising operations.
Mr Farage said he was "delighted" by the outcome of the election and was standing down at a time when the party had "never been more successful".
Leadership ballot papers were sent to UKIP members earlier this month and they had until Thursday to vote.
UKIP LEADERSHIP RESULT
Lord Pearson: 4,743
Gerard Batten: 2,571
Nikki Sinclaire: 1,214
Mike Nattrass: 1,092
Alan Wood: 315
The contest had seen some controversy, with Mr Farage claiming that Lord Pearson, a former insurance broker, was "head and shoulders" above his rivals and any other winner could prove "tricky" for the party.
Mr Batten said that such comments were an "insult" and might "unduly influence" the outcome.
UKIP, which wants the UK to withdraw from the EU, took 13 seats at the European elections but has no MPs at Westminster.
Mr Farage is running for the seat of Buckingham at the next general election, where he hopes to oust Commons Speaker John Bercow.
Despite relinquishing the party leadership, the BBC's Political Correspondent Iain Watson said Mr Farage was still likely to remain UKIP's main spokesman and most prominent figure.
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