Born on 31 July 1983, Tonin grew up in Kamnik just north of Ljubljana, and studied political sciences at the Ljubljana Faculty of Social Sciences. His MBA thesis focused on Slovenia's independence efforts and economic effects of independence.
He became involved in politics in 2001, when he entered the local branch of the conservative Christian democratic NSi party in Kamnik. Since 2006, he has also served as city councillor in Kamnik.
Kamnik is where Marjan Šarec, the surprise runner-up in the 2017 presidential election whose party came second in the 3 June election again, has been serving as mayor since 2010. And it was apparently Šarec who put forward Tonin as a joint candidate of a potential emerging coalition for the speaker.
Tonin collected his political experience in the NSi's youth wing, where he also served as vice-president for a while. His team from that period still forms the core of his supporters within the party today.
He started advising the NSi parliamentary group on public relations in 2007 and was elected MP four years later. He has served two four-year terms in parliament so far, each time acting as NSi deputy group head.
In late January he took over as NSi leader upon resignation of Ljudmila Novak, who had led the party for almost a decade.
When appointed full-fledged party president in April, Tonin declared that the party would double the number of seats in parliament. He tendered his resignation immediately after it became clear on election night that the party had not achieved the goal, winning seven seats.
However, the party rejected his resignation, assessing that the showing was a success considering the party increased the number of MPs from five won in 2014.
The change at the helm of the party just months before the general election was deemed risky by many pundits. But the gamble paid off, possibly because Tonin - as opposed to Novak - is not avert to cooperating with the Democrats (SDS), the party that won the 3 June election.
His openness to cooperation with parties on both sides of the spectrum is what ensured him the position of speaker, but some believe he will only stay in the post for a little while, until a coalition is formed.
The coalition that appears to be emerging around Šarec was unable to find a candidate among their own ranks, while the centre-right parties do not have enough votes to appoint a candidate on their own.
But the appointment of Tonin in itself is an indicator that Slovenia might get a rainbow coalition.
The latest Vox Populi opinion poll ranked him the 11th most popular Slovenian politician, just behind Luka Mesec, the head of the Left, the only party that did not express support for Tonin becoming speaker.
Tonin is married, has two daughters and a third child on the way. He spends his free time with his family and doing sports.
His party colleagues see him as a dedicated politician with vision. In 2016, he presented his political agenda in a book entitled Hope for Slovenia (Upanje za Slovenijo).
Although he will turn 35 in just over a month, Tonin is not the youngest speaker Slovenia has ever had. In 1994 Jožef Školč was appointed speaker less than a month after turning 34.