The "Right2Change" protest brought together a range of anti-austerity groups under the banner of opposing controversial water charges, which have crystallised anger at a rise in poverty, budget cuts and tax hikes since an economic crisis and bailout in 2010.
Protesters carried colourful flags and banners reading "Can't Pay Won't Pay" and "Water is a Human Right", and chanted: "Banks Got Bailed Out, We Got Sold Out".
"We are fighting to end to the austerity that has crippled people in this country. Water was the straw that broke the camel's back," said June Markham, a retiree from Dublin.
Organisers said the protest was for an Ireland "not based on cronyism, corruption or greed, but instead one based on equality, democracy and social justice".
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Polls ahead of the election on February 26 show Ireland may be the latest eurozone country to face political uncertainty as prime minister Enda Kenny and his current coalition government could struggle to form a majority for a second term.
The march was also supported by left-leaning republican party Sinn Fein, which has boosted its support with an anti-austerity stance, and leader Gerry Adams joined the crowds to address a rally.
Ireland goes to the polls on Friday with the outgoing coalition of Fine Gael and Labour seeking a second term on a platform of keeping the economy steady.
The eurozone nation has the highest economic growth rate in the European Union -- 7.0 per cent in the first nine months of last year -- but many voters say they are not feeling the benefit and are disillusioned after years of sacrifices and a financial crisis that has discredited Ireland's elite.