The 38-year-old was handed a clear victory, with more than 89 percent of party supporters backing him to remain as chief.
But all agree that the pony-tailed former university lecturer has shaken up politics since taking the reins of Podemos, uprooting Spain's traditional two-party system and transforming his party into the country's third most powerful political force.
But after years of fighting against the establishment, he faced a far more personal struggle at a weekend party congress as supporters voted on whether to back him and his strategy for Podemos' future after months of bitter in-fighting.
He need not have worried.
The 38-year-old was handed a clear victory, with more than 89 percent of party supporters backing him to remain as chief and a large majority of his candidates chosen for the leadership council.
Supporters also backed his strategy for Podemos to fight on as an anti-establishment street movement, in what supporters hope will end months of bitter divisions in one of Europe's leading far-left parties.
"The wind of change continues to blow," he told thousands of cheering supporters.
Bearded and with a solemn gaze that is regularly broken by a winning smile, Iglesias vows to defend those left behind in a country stricken by sky-high unemployment, inequalities and corruption.
A brilliant orator and strategist, Iglesias has managed to harness the anger of Spain's Indignados anti-austerity street movement into an influential political force.
He created Podemos in January 2014 along with colleagues from Madrid's Complutense University where he taught.
Four months later, it won 1.2 million votes and five seats in elections for the European parliament.
Then Podemos came third in December 2015 elections and again in repeat polls in June 2016, uprooting the traditional dominance of the conservative Popular Party and the Socialists.
Buoyed by promises of radical change and a more egalitarian society, Podemos won 71 seats in parliament as part of a wider leftwing coalition.
But it has found itself riven by competing visions of how to eventually achieve its goal of governing Spain.
Iglesias argued that Podemos, which harnessed the anger of millions stung by Spain's economic woes, should take to the streets again as an anti-establishment group.
His deputy Inigo Errejon meanwhile wanted the party to work purely from within parliament and shed its "enfant terrible" image.
On Sunday, Iglesias won, with 56 percent of voters backing his strategy for the party.
Raised in the working-class Madrid neighbourhood of Vallecas where he still lives in a modest flat, his parents gave him the name of Socialist party founder Pablo Iglesias Posse -- in front of whose grave they met.
In contrast with Posse, a humble typographer, the Podemos leader has a raft of diplomas in politics, law and communication.
Immersed in politics from an early age, Iglesias was active in the communist youth and anti-globalisation movements before the Indignados protest wave erupted in Spain in 2011 at the height of the economic crisis.
He can be cutting one moment, and gentle the next.
In his 2011 thesis on Evo Morales's left-wing party in Bolivia, Errejon thanked Iglesias, "a comrade with a sharp mind and Bolshevik drive" who had taught him about "the art of war" and how to practise it "methodically and with persistence".
His vehement speeches have divided opinion.
But he can also come across as funny and accessible, playing his guitar live on television, giving a ride to a presenter on his red scooter or quoting from TV series such as "Game of Thrones" or "The Simpsons".
One of his teachers, Ramon Cotarelo, remembers him as a "considerate" person and "brilliant" student.
But former colleague Antonio Elorza was not so flattering in his assessment. "You couldn't trust him. He would do whatever he pleased, didn't defend any just cause so as not to lose an ounce of power," he said.