The 43-year-old historian sparked outrage in the Baltic eurozone state for flashing a hand gesture resembling the OK sign used by white supremacists as he was sworn into office before parliament in April.
He also infamously said of migrants "if they're black, show them the door" on a Tallinn municipal TV channel in 2013 while discussing riots in Sweden, adding "I want Estonia to be a white country".
Helme is deputy leader of the eurosceptic Estonian Conservative People's Party (EKRE) founded in 2012 by his father Mart Helme, who is still its leader.
The party nearly tripled its seats in the March general election, coming a close third behind the left-leaning Centre party, and liberal Reform -- both establishment parties.
Its appeal is largely rooted in the misgivings of rural Estonians who feel left behind after years of austerity under Centre and Reform, local analysts say.
The EKRE became the first far-right party to enter Estonia's government when it joined the three-party coalition of Centre party Prime Minister Juri Ratas in April.
Helme has been a vocal opponent of Estonia's membership of the eurozone, which it joined in 2011.
Years of tight spending under previous governments has given the cyber-savvy Baltic state of 1.3 million people the bloc's lowest debt-to-GDP ratio.
As finance minister, Helme has called for tighter anti-money laundering rules in the wake of a massive scandal that saw some 200 billion euros ($225 million) of dubious origin channelled through Danske Bank's Estonian branch between 2007 and 2015.
Other than this, he has said little on fiscal matters.
Seat in Strasbourg?
Both Helme and his father had threatened riots should they fail to secure a coalition deal as talks were under way in March.
Claiming they had been misunderstood, they later denied suggesting unrest and blamed the media for twisting their words.
Their party's rise reflects a trend of voter frustration that has seen far-right, anti-migrant groups gain ground in recent parliamentary elections across the EU.
Since entering government, the Helmes have backed off from their idea of holding an "Estxit" referendum on Estonia's EU membership, as the move would fail in the overwhelmingly pro-EU country.
Their deep suspicion towards Moscow means they see Estonia's NATO membership as a must.
Both Helmes are running in elections to the European parliament on May 26th and hope to join European far-right parties allied with France’s Marine Le Pen and Italy's Matteo Salvini.
Before entering politics, Helme junior owned a jazz cafe that went bankrupt, worked as foreign news editor for a leading Estonian news portal and headed a publishing house specialising in books about art.
But he is best known for his aggressive far-right political rhetoric, particularly concerning migrants, the medical community, the media and climate change.
Like his father, Helme junior is also hostile to most media outlets and recently demanded Estonian public broadcaster ERR punish what he called its "biased" journalists.
Martin Helme sparked outrage in the medical community in March by accusing doctors performing abortions of breaking their Hippocratic oath, while his father compared abortion to murder.
Both men support the death penalty.
Like his father, Helme also believes that there is no evidence to indicate that humans are contributing to climate change.
"There have never been as many polar bears as there are now," he claimed during the election campaign, insisting that what he termed "ecology hysteria" must stop.